This patch adds a new generic streaming logic for audio over USB.

It defines a model (snd_usb_endpoint) that handles everything that is related to an USB endpoint and its streaming. There are functions to activate and deactivate an endpoint (which call usb_set_interface()), and to start and stop its URBs. It also has function pointers to be called when data was received or is about to be sent, and pointer to a sync slave (another snd_usb_endpoint) that is informed when data has been received.

A snd_usb_endpoint knows about its state and implements a refcounting, so only the first user will actually start the URBs and only the last one to stop it will tear them down again.

With this sort of abstraction, the actual streaming is decoupled from the pcm handling, which makes the "implicit feedback" mechanisms easy to implement.

In order to split changes properly, this patch only adds the new implementation but leaves the old one around, so the the driver doesn't change its behaviour. The switch to actually use the new code is submitted separately.

Signed-off-by: Daniel Mack zonque@gmail.com --- sound/usb/card.h | 58 ++++ sound/usb/endpoint.c | 929 +++++++++++++++++++++++++++++++++++++++++++++++++- sound/usb/endpoint.h | 26 ++ sound/usb/usbaudio.h | 1 + 4 files changed, 1003 insertions(+), 11 deletions(-)

diff --git a/sound/usb/card.h b/sound/usb/card.h index da5fa1a..9acbd4a 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -30,13 +30,17 @@ struct audioformat { };

struct snd_usb_substream; +struct snd_usb_endpoint;

struct snd_urb_ctx { struct urb *urb; unsigned int buffer_size; /* size of data buffer, if data URB */ struct snd_usb_substream *subs; + struct snd_usb_endpoint *ep; int index; /* index for urb array */ int packets; /* number of packets per urb */ + int packet_size[MAX_PACKS_HS]; /* size of packets for next submission */ + struct list_head ready_list; };

struct snd_urb_ops { @@ -46,6 +50,60 @@ struct snd_urb_ops { int (*retire_sync)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u); };

+struct snd_usb_endpoint { + struct snd_usb_audio *chip; + + int use_count; + int ep_num; /* the referenced endpoint number */ + int type; /* SND_USB_ENDPOINT_TYPE_* */ + unsigned long flags; + + void (*prepare_data_urb) (struct snd_usb_substream *subs, + struct urb *urb); + void (*retire_data_urb) (struct snd_usb_substream *subs, + struct urb *urb); + + struct snd_usb_substream *data_subs; + struct snd_usb_endpoint *sync_master; + struct snd_usb_endpoint *sync_slave; + + struct snd_urb_ctx urb[MAX_URBS]; + + struct snd_usb_packet_info { + uint32_t packet_size[MAX_PACKS_HS]; + int packets; + } next_packet[MAX_URBS]; + int next_packet_read_pos, next_packet_write_pos; + struct list_head ready_playback_urbs; + + unsigned int nurbs; /* # urbs */ + unsigned long active_mask; /* bitmask of active urbs */ + unsigned long unlink_mask; /* bitmask of unlinked urbs */ + char *syncbuf; /* sync buffer for all sync URBs */ + dma_addr_t sync_dma; /* DMA address of syncbuf */ + + unsigned int pipe; /* the data i/o pipe */ + unsigned int freqn; /* nominal sampling rate in fs/fps in Q16.16 format */ + unsigned int freqm; /* momentary sampling rate in fs/fps in Q16.16 format */ + int freqshift; /* how much to shift the feedback value to get Q16.16 */ + unsigned int freqmax; /* maximum sampling rate, used for buffer management */ + unsigned int phase; /* phase accumulator */ + unsigned int maxpacksize; /* max packet size in bytes */ + unsigned int maxframesize; /* max packet size in frames */ + unsigned int curpacksize; /* current packet size in bytes (for capture) */ + unsigned int curframesize; /* current packet size in frames (for capture) */ + unsigned int syncmaxsize; /* sync endpoint packet size */ + unsigned int fill_max:1; /* fill max packet size always */ + unsigned int datainterval; /* log_2 of data packet interval */ + unsigned int syncinterval; /* P for adaptive mode, 0 otherwise */ + unsigned char silence_value; + unsigned int stride; + int iface, alt_idx; + + spinlock_t lock; + struct list_head list; +}; + struct snd_usb_substream { struct snd_usb_stream *stream; struct usb_device *dev; diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 08dcce5..56f1810 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -20,9 +20,11 @@ #include <linux/ratelimit.h> #include <linux/usb.h> #include <linux/usb/audio.h> +#include <linux/slab.h>

#include <sound/core.h> #include <sound/pcm.h> +#include <sound/pcm_params.h>

#include "usbaudio.h" #include "helper.h" @@ -30,6 +32,9 @@ #include "endpoint.h" #include "pcm.h"

+#define EP_FLAG_ACTIVATED 0 +#define EP_FLAG_RUNNING 1 + /* * convert a sampling rate into our full speed format (fs/1000 in Q16.16) * this will overflow at approx 524 kHz @@ -51,7 +56,7 @@ static inline unsigned get_usb_high_speed_rate(unsigned int rate) /* * unlink active urbs. */ -static int deactivate_urbs(struct snd_usb_substream *subs, int force, int can_sleep) +static int deactivate_urbs_old(struct snd_usb_substream *subs, int force, int can_sleep) { struct snd_usb_audio *chip = subs->stream->chip; unsigned int i; @@ -113,7 +118,7 @@ static void release_urb_ctx(struct snd_urb_ctx *u) /* * wait until all urbs are processed. */ -static int wait_clear_urbs(struct snd_usb_substream *subs) +static int wait_clear_urbs_old(struct snd_usb_substream *subs) { unsigned long end_time = jiffies + msecs_to_jiffies(1000); unsigned int i; @@ -148,8 +153,8 @@ void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force) int i;

/* stop urbs (to be sure) */ - deactivate_urbs(subs, force, 1); - wait_clear_urbs(subs); + deactivate_urbs_old(subs, force, 1); + wait_clear_urbs_old(subs);

for (i = 0; i < MAX_URBS; i++) release_urb_ctx(&subs->dataurb[i]); @@ -164,7 +169,7 @@ void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force) /* * complete callback from data urb */ -static void snd_complete_urb(struct urb *urb) +static void snd_complete_urb_old(struct urb *urb) { struct snd_urb_ctx *ctx = urb->context; struct snd_usb_substream *subs = ctx->subs; @@ -318,7 +323,7 @@ int snd_usb_init_substream_urbs(struct snd_usb_substream *subs, u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP; u->urb->interval = 1 << subs->datainterval; u->urb->context = u; - u->urb->complete = snd_complete_urb; + u->urb->complete = snd_complete_urb_old; }

if (subs->syncpipe) { @@ -856,7 +861,7 @@ static int start_urbs(struct snd_usb_substream *subs, struct snd_pcm_runtime *ru

__error: // snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN); - deactivate_urbs(subs, 0, 0); + deactivate_urbs_old(subs, 0, 0); return -EPIPE; }

@@ -917,7 +922,7 @@ int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substream, int subs->ops.prepare = prepare_playback_urb; return 0; case SNDRV_PCM_TRIGGER_STOP: - return deactivate_urbs(subs, 0, 0); + return deactivate_urbs_old(subs, 0, 0); case SNDRV_PCM_TRIGGER_PAUSE_PUSH: subs->ops.prepare = prepare_nodata_playback_urb; return 0; @@ -935,7 +940,7 @@ int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream, int c subs->ops.retire = retire_capture_urb; return start_urbs(subs, substream->runtime); case SNDRV_PCM_TRIGGER_STOP: - return deactivate_urbs(subs, 0, 0); + return deactivate_urbs_old(subs, 0, 0); case SNDRV_PCM_TRIGGER_PAUSE_PUSH: subs->ops.retire = retire_paused_capture_urb; return 0; @@ -951,8 +956,8 @@ int snd_usb_substream_prepare(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime) { /* clear urbs (to be sure) */ - deactivate_urbs(subs, 0, 1); - wait_clear_urbs(subs); + deactivate_urbs_old(subs, 0, 1); + wait_clear_urbs_old(subs);

/* for playback, submit the URBs now; otherwise, the first hwptr_done * updates for all URBs would happen at the same time when starting */ @@ -964,3 +969,905 @@ int snd_usb_substream_prepare(struct snd_usb_substream *subs, return 0; }

+int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep) +{ + return ep->sync_master && + ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA && + ep->type == SND_USB_ENDPOINT_TYPE_DATA && + usb_pipeout(ep->pipe); +} + +/* determine the number of frames in the next packet */ +static int next_packet_size(struct snd_usb_endpoint *ep) +{ + unsigned long flags; + int ret; + + if (ep->fill_max) + return ep->maxframesize; + + spin_lock_irqsave(&ep->lock, flags); + ep->phase = (ep->phase & 0xffff) + + (ep->freqm << ep->datainterval); + ret = min(ep->phase >> 16, ep->maxframesize); + spin_unlock_irqrestore(&ep->lock, flags); + + return ret; +} + +static void retire_outbound_urb(struct snd_usb_endpoint *ep, + struct snd_urb_ctx *urb_ctx) +{ + if (ep->retire_data_urb) + ep->retire_data_urb(ep->data_subs, urb_ctx->urb); +} + +static void retire_inbound_urb(struct snd_usb_endpoint *ep, + struct snd_urb_ctx *urb_ctx) +{ + struct urb *urb = urb_ctx->urb; + + if (ep->sync_slave) + snd_usb_handle_sync_urb(ep->sync_slave, ep, urb); + + if (ep->retire_data_urb) + ep->retire_data_urb(ep->data_subs, urb); +} + +static void prepare_outbound_urb_sizes(struct snd_usb_endpoint *ep, + struct snd_urb_ctx *ctx) +{ + int i; + + for (i = 0; i < ctx->packets; ++i) + ctx->packet_size[i] = next_packet_size(ep); +} + +/* + * Prepare a PLAYBACK urb for submission to the bus. + */ +static void prepare_outbound_urb(struct snd_usb_endpoint *ep, + struct snd_urb_ctx *ctx) +{ + int i; + struct urb *urb = ctx->urb; + unsigned char *cp = urb->transfer_buffer; + + urb->dev = ep->chip->dev; /* we need to set this at each time */ + + switch (ep->type) { + case SND_USB_ENDPOINT_TYPE_DATA: + if (ep->prepare_data_urb) { + ep->prepare_data_urb(ep->data_subs, urb); + } else { + /* no data provider, so send silence */ + unsigned int offs = 0; + for (i = 0; i < ctx->packets; ++i) { + int counts = ctx->packet_size[i]; + urb->iso_frame_desc[i].offset = offs * ep->stride; + urb->iso_frame_desc[i].length = counts * ep->stride; + offs += counts; + } + + urb->number_of_packets = ctx->packets; + urb->transfer_buffer_length = offs * ep->stride; + memset(urb->transfer_buffer, ep->silence_value, + offs * ep->stride); + } + break; + + case SND_USB_ENDPOINT_TYPE_SYNC: + if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) { + /* + * fill the length and offset of each urb descriptor. + * the fixed 12.13 frequency is passed as 16.16 through the pipe. + */ + urb->iso_frame_desc[0].length = 4; + urb->iso_frame_desc[0].offset = 0; + cp[0] = ep->freqn; + cp[1] = ep->freqn >> 8; + cp[2] = ep->freqn >> 16; + cp[3] = ep->freqn >> 24; + } else { + /* + * fill the length and offset of each urb descriptor. + * the fixed 10.14 frequency is passed through the pipe. + */ + urb->iso_frame_desc[0].length = 3; + urb->iso_frame_desc[0].offset = 0; + cp[0] = ep->freqn >> 2; + cp[1] = ep->freqn >> 10; + cp[2] = ep->freqn >> 18; + } + + break; + } +} + +/* + * Prepare a CAPTURE or SYNC urb for submission to the bus. + */ +static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep, + struct snd_urb_ctx *urb_ctx) +{ + int i, offs; + struct urb *urb = urb_ctx->urb; + + urb->dev = ep->chip->dev; /* we need to set this at each time */ + + switch (ep->type) { + case SND_USB_ENDPOINT_TYPE_DATA: + offs = 0; + for (i = 0; i < urb_ctx->packets; i++) { + urb->iso_frame_desc[i].offset = offs; + urb->iso_frame_desc[i].length = ep->curpacksize; + offs += ep->curpacksize; + } + + urb->transfer_buffer_length = offs; + urb->number_of_packets = urb_ctx->packets; + break; + + case SND_USB_ENDPOINT_TYPE_SYNC: + urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize); + urb->iso_frame_desc[0].offset = 0; + break; + } +} + +static void queue_pending_output_urbs(struct snd_usb_endpoint *ep) +{ + while (test_bit(EP_FLAG_RUNNING, &ep->flags)) { + + unsigned long flags; + struct snd_usb_packet_info *packet; + struct snd_urb_ctx *ctx = NULL; + struct urb *urb; + int err, i; + + spin_lock_irqsave(&ep->lock, flags); + if (ep->next_packet_read_pos != ep->next_packet_write_pos) { + packet = ep->next_packet + ep->next_packet_read_pos; + ep->next_packet_read_pos++; + ep->next_packet_read_pos %= MAX_URBS; + + /* take URB out of FIFO */ + if (!list_empty(&ep->ready_playback_urbs)) + ctx = list_first_entry(&ep->ready_playback_urbs, + struct snd_urb_ctx, ready_list); + } + spin_unlock_irqrestore(&ep->lock, flags); + + if (ctx == NULL) + return; + + list_del_init(&ctx->ready_list); + urb = ctx->urb; + + /* copy over the length information */ + for (i = 0; i < packet->packets; i++) + ctx->packet_size[i] = packet->packet_size[i]; + + prepare_outbound_urb(ep, ctx); + + err = usb_submit_urb(ctx->urb, GFP_ATOMIC); + if (err < 0) + snd_printk(KERN_ERR "Unable to submit urb #%d: %d (urb %p)\n", + ctx->index, err, ctx->urb); + else + set_bit(ctx->index, &ep->active_mask); + } +} + +/* + * complete callback for urbs + */ +static void snd_complete_urb(struct urb *urb) +{ + struct snd_urb_ctx *ctx = urb->context; + struct snd_usb_endpoint *ep = ctx->ep; + int err; + + if (unlikely(urb->status == -ENOENT || /* unlinked */ + urb->status == -ENODEV || /* device removed */ + urb->status == -ECONNRESET || /* unlinked */ + urb->status == -ESHUTDOWN || /* device disabled */ + ep->chip->shutdown)) /* device disconnected */ + goto exit_clear; + + if (usb_pipeout(ep->pipe)) { + retire_outbound_urb(ep, ctx); + /* can be stopped during retire callback */ + if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags))) + goto exit_clear; + + if (snd_usb_endpoint_implict_feedback_sink(ep)) { + unsigned long flags; + + spin_lock_irqsave(&ep->lock, flags); + list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs); + spin_unlock_irqrestore(&ep->lock, flags); + queue_pending_output_urbs(ep); + + goto exit_clear; + } + + prepare_outbound_urb_sizes(ep, ctx); + prepare_outbound_urb(ep, ctx); + } else { + retire_inbound_urb(ep, ctx); + /* can be stopped during retire callback */ + if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags))) + goto exit_clear; + + prepare_inbound_urb(ep, ctx); + } + + err = usb_submit_urb(urb, GFP_ATOMIC); + if (err == 0) + return; + + snd_printk(KERN_ERR "cannot submit urb (err = %d)\n", err); + //snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN); + +exit_clear: + clear_bit(ctx->index, &ep->active_mask); +} + +struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip, + struct usb_host_interface *alts, + int ep_num, int direction, int type) +{ + struct list_head *p; + struct snd_usb_endpoint *ep; + int ret, is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK; + + mutex_lock(&chip->mutex); + + list_for_each(p, &chip->ep_list) { + ep = list_entry(p, struct snd_usb_endpoint, list); + if (ep->ep_num == ep_num && + ep->iface == alts->desc.bInterfaceNumber && + ep->alt_idx == alts->desc.bAlternateSetting) { + snd_printdd(KERN_DEBUG "Re-using EP %x in iface %d,%d @%p\n", + ep_num, ep->iface, ep->alt_idx, ep); + goto __exit_unlock; + } + } + + snd_printdd(KERN_DEBUG "Creating new %s %s endpoint #%x\n", + is_playback ? "playback" : "capture", + type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync", + ep_num); + + /* select the alt setting once so the endpoints become valid */ + ret = usb_set_interface(chip->dev, alts->desc.bInterfaceNumber, + alts->desc.bAlternateSetting); + if (ret < 0) { + snd_printk(KERN_ERR "%s(): usb_set_interface() failed, ret = %d\n", + __func__, ret); + ep = NULL; + goto __exit_unlock; + } + + ep = kzalloc(sizeof(*ep), GFP_KERNEL); + if (!ep) + goto __exit_unlock; + + ep->chip = chip; + spin_lock_init(&ep->lock); + ep->type = type; + ep->ep_num = ep_num; + ep->iface = alts->desc.bInterfaceNumber; + ep->alt_idx = alts->desc.bAlternateSetting; + INIT_LIST_HEAD(&ep->ready_playback_urbs); + ep_num &= USB_ENDPOINT_NUMBER_MASK; + + if (is_playback) + ep->pipe = usb_sndisocpipe(chip->dev, ep_num); + else + ep->pipe = usb_rcvisocpipe(chip->dev, ep_num); + + if (type == SND_USB_ENDPOINT_TYPE_SYNC) { + if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE && + get_endpoint(alts, 1)->bRefresh >= 1 && + get_endpoint(alts, 1)->bRefresh <= 9) + ep->syncinterval = get_endpoint(alts, 1)->bRefresh; + else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) + ep->syncinterval = 1; + else if (get_endpoint(alts, 1)->bInterval >= 1 && + get_endpoint(alts, 1)->bInterval <= 16) + ep->syncinterval = get_endpoint(alts, 1)->bInterval - 1; + else + ep->syncinterval = 3; + + ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize); + } + + list_add_tail(&ep->list, &chip->ep_list); + +__exit_unlock: + mutex_unlock(&chip->mutex); + + return ep; +} + +/* + * wait until all urbs are processed. + */ +static int wait_clear_urbs(struct snd_usb_endpoint *ep) +{ + unsigned long end_time = jiffies + msecs_to_jiffies(1000); + unsigned int i; + int alive; + + do { + alive = 0; + for (i = 0; i < ep->nurbs; i++) + if (test_bit(i, &ep->active_mask)) + alive++; + + if (!alive) + break; + + schedule_timeout_uninterruptible(1); + } while (time_before(jiffies, end_time)); + + if (alive) + snd_printk(KERN_ERR "timeout: still %d active urbs on EP #%x\n", + alive, ep->ep_num); + + return 0; +} + +/* + * unlink active urbs. + */ +static int deactivate_urbs(struct snd_usb_endpoint *ep, int force, int can_sleep) +{ + unsigned long flags; + unsigned int i; + int async; + + if (!force && ep->chip->shutdown) /* to be sure... */ + return -EBADFD; + + async = !can_sleep && ep->chip->async_unlink; + + clear_bit(EP_FLAG_RUNNING, &ep->flags); + + INIT_LIST_HEAD(&ep->ready_playback_urbs); + ep->next_packet_read_pos = 0; + ep->next_packet_write_pos = 0; + + if (!async && in_interrupt()) + return 0; + + for (i = 0; i < ep->nurbs; i++) { + if (test_bit(i, &ep->active_mask)) { + if (!test_and_set_bit(i, &ep->unlink_mask)) { + struct urb *u = ep->urb[i].urb; + if (async) + usb_unlink_urb(u); + else + usb_kill_urb(u); + } + } + } + + return 0; +} + +/* + * release an endpoint's urbs + */ +static void release_urbs(struct snd_usb_endpoint *ep, int force) +{ + int i; + + /* route incoming urbs to nirvana */ + ep->retire_data_urb = NULL; + ep->prepare_data_urb = NULL; + + /* stop urbs */ + deactivate_urbs(ep, force, 1); + wait_clear_urbs(ep); + + for (i = 0; i < ep->nurbs; i++) + release_urb_ctx(&ep->urb[i]); + + if (ep->syncbuf) + usb_free_coherent(ep->chip->dev, SYNC_URBS * 4, + ep->syncbuf, ep->sync_dma); + + ep->syncbuf = NULL; + ep->nurbs = 0; +} + +static int data_ep_set_params(struct snd_usb_endpoint *ep, + struct snd_pcm_hw_params *hw_params, + struct audioformat *fmt, + struct snd_usb_endpoint *sync_ep) +{ + unsigned int maxsize, i, urb_packs, total_packs, packs_per_ms; + int period_bytes = params_period_bytes(hw_params); + int format = params_format(hw_params); + int is_playback = usb_pipeout(ep->pipe); + int frame_bits = snd_pcm_format_physical_width(params_format(hw_params)) * + params_channels(hw_params); + + ep->datainterval = fmt->datainterval; + ep->stride = frame_bits >> 3; + ep->silence_value = format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0; + + /* calculate max. frequency */ + if (ep->maxpacksize) { + /* whatever fits into a max. size packet */ + maxsize = ep->maxpacksize; + ep->freqmax = (maxsize / (frame_bits >> 3)) + << (16 - ep->datainterval); + } else { + /* no max. packet size: just take 25% higher than nominal */ + ep->freqmax = ep->freqn + (ep->freqn >> 2); + maxsize = ((ep->freqmax + 0xffff) * (frame_bits >> 3)) + >> (16 - ep->datainterval); + } + + if (ep->fill_max) + ep->curpacksize = ep->maxpacksize; + else + ep->curpacksize = maxsize; + + if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) + packs_per_ms = 8 >> ep->datainterval; + else + packs_per_ms = 1; + + if (is_playback && !snd_usb_endpoint_implict_feedback_sink(ep)) { + urb_packs = max(ep->chip->nrpacks, 1); + urb_packs = min(urb_packs, (unsigned int) MAX_PACKS); + } else { + urb_packs = 1; + } + + urb_packs *= packs_per_ms; + + if (sync_ep && !snd_usb_endpoint_implict_feedback_sink(ep)) + urb_packs = min(urb_packs, 1U << sync_ep->syncinterval); + + /* decide how many packets to be used */ + if (is_playback && !snd_usb_endpoint_implict_feedback_sink(ep)) { + unsigned int minsize, maxpacks; + /* determine how small a packet can be */ + minsize = (ep->freqn >> (16 - ep->datainterval)) + * (frame_bits >> 3); + /* with sync from device, assume it can be 12% lower */ + if (sync_ep) + minsize -= minsize >> 3; + minsize = max(minsize, 1u); + total_packs = (period_bytes + minsize - 1) / minsize; + /* we need at least two URBs for queueing */ + if (total_packs < 2) { + total_packs = 2; + } else { + /* and we don't want too long a queue either */ + maxpacks = max(MAX_QUEUE * packs_per_ms, urb_packs * 2); + total_packs = min(total_packs, maxpacks); + } + } else { + while (urb_packs > 1 && urb_packs * maxsize >= period_bytes) + urb_packs >>= 1; + total_packs = MAX_URBS * urb_packs; + } + + ep->nurbs = (total_packs + urb_packs - 1) / urb_packs; + if (ep->nurbs > MAX_URBS) { + /* too much... */ + ep->nurbs = MAX_URBS; + total_packs = MAX_URBS * urb_packs; + } else if (ep->nurbs < 2) { + /* too little - we need at least two packets + * to ensure contiguous playback/capture + */ + ep->nurbs = 2; + } + + /* allocate and initialize data urbs */ + for (i = 0; i < ep->nurbs; i++) { + struct snd_urb_ctx *u = &ep->urb[i]; + u->index = i; + u->ep = ep; + u->packets = (i + 1) * total_packs / ep->nurbs + - i * total_packs / ep->nurbs; + u->buffer_size = maxsize * u->packets; + + if (fmt->fmt_type == UAC_FORMAT_TYPE_II) + u->packets++; /* for transfer delimiter */ + u->urb = usb_alloc_urb(u->packets, GFP_KERNEL); + if (!u->urb) + goto out_of_memory; + + u->urb->transfer_buffer = + usb_alloc_coherent(ep->chip->dev, u->buffer_size, + GFP_KERNEL, &u->urb->transfer_dma); + if (!u->urb->transfer_buffer) + goto out_of_memory; + u->urb->pipe = ep->pipe; + u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP; + u->urb->interval = 1 << ep->datainterval; + u->urb->context = u; + u->urb->complete = snd_complete_urb; + INIT_LIST_HEAD(&u->ready_list); + } + + return 0; + +out_of_memory: + release_urbs(ep, 0); + return -ENOMEM; +} + +static int sync_ep_set_params(struct snd_usb_endpoint *ep, + struct snd_pcm_hw_params *hw_params, + struct audioformat *fmt) +{ + int i; + + ep->syncbuf = usb_alloc_coherent(ep->chip->dev, SYNC_URBS * 4, + GFP_KERNEL, &ep->sync_dma); + if (!ep->syncbuf) + return -ENOMEM; + + for (i = 0; i < SYNC_URBS; i++) { + struct snd_urb_ctx *u = &ep->urb[i]; + u->index = i; + u->ep = ep; + u->packets = 1; + u->urb = usb_alloc_urb(1, GFP_KERNEL); + if (!u->urb) + goto out_of_memory; + u->urb->transfer_buffer = ep->syncbuf + i * 4; + u->urb->transfer_dma = ep->sync_dma + i * 4; + u->urb->transfer_buffer_length = 4; + u->urb->pipe = ep->pipe; + u->urb->transfer_flags = URB_ISO_ASAP | + URB_NO_TRANSFER_DMA_MAP; + u->urb->number_of_packets = 1; + u->urb->interval = 1 << ep->syncinterval; + u->urb->context = u; + u->urb->complete = snd_complete_urb; + } + + ep->nurbs = SYNC_URBS; + + return 0; + +out_of_memory: + release_urbs(ep, 0); + return -ENOMEM; +} + +int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, + struct snd_pcm_hw_params *hw_params, + struct audioformat *fmt, + struct snd_usb_endpoint *sync_ep) +{ + int err; + + if (ep->use_count != 0) { + snd_printk(KERN_WARNING "Unable to change format on ep #%x: already in use\n", + ep->ep_num); + return -EBUSY; + } + + /* release old buffers, if any */ + release_urbs(ep, 0); + + ep->datainterval = fmt->datainterval; + ep->maxpacksize = fmt->maxpacksize; + ep->fill_max = fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX; + + if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_FULL) + ep->freqn = get_usb_full_speed_rate(params_rate(hw_params)); + else + ep->freqn = get_usb_high_speed_rate(params_rate(hw_params)); + + /* calculate the frequency in 16.16 format */ + ep->freqm = ep->freqn; + ep->freqshift = INT_MIN; + + ep->phase = 0; + + switch (ep->type) { + case SND_USB_ENDPOINT_TYPE_DATA: + err = data_ep_set_params(ep, hw_params, fmt, sync_ep); + break; + case SND_USB_ENDPOINT_TYPE_SYNC: + err = sync_ep_set_params(ep, hw_params, fmt); + break; + default: + err = -EINVAL; + } + + snd_printdd(KERN_DEBUG "Setting params for ep #%x (type %d, %d urbs), ret=%d\n", + ep->ep_num, ep->type, ep->nurbs, err); + + return err; +} + +int snd_usb_endpoint_start(struct snd_usb_endpoint *ep) +{ + int err; + unsigned int i; + + if (ep->chip->shutdown) + return -EBADFD; + + /* already running? */ + if (++ep->use_count != 1) + return 0; + + if (snd_BUG_ON(!test_bit(EP_FLAG_ACTIVATED, &ep->flags))) + return -EINVAL; + + /* just to be sure */ + deactivate_urbs(ep, 0, 1); + wait_clear_urbs(ep); + + ep->active_mask = 0; + ep->unlink_mask = 0; + ep->phase = 0; + + /* + * If this endpoint has a data endpoint as implicit feedback source, + * don't start the urbs here. Instead, mark them all as available, + * wait for the record urbs to arrive and queue from that context. + */ + + set_bit(EP_FLAG_RUNNING, &ep->flags); + + if (snd_usb_endpoint_implict_feedback_sink(ep)) { + for (i = 0; i < ep->nurbs; i++) { + struct snd_urb_ctx *ctx = ep->urb + i; + list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs); + } + + return 0; + } + + for (i = 0; i < ep->nurbs; i++) { + struct urb *urb = ep->urb[i].urb; + + if (snd_BUG_ON(!urb)) + goto __error; + + if (usb_pipeout(ep->pipe)) { + prepare_outbound_urb_sizes(ep, urb->context); + prepare_outbound_urb(ep, urb->context); + } else { + prepare_inbound_urb(ep, urb->context); + } + + err = usb_submit_urb(urb, GFP_ATOMIC); + if (err < 0) { + snd_printk(KERN_ERR "cannot submit urb %d, error %d: %s\n", + i, err, usb_error_string(err)); + goto __error; + } + set_bit(i, &ep->active_mask); + } + + return 0; + +__error: + clear_bit(EP_FLAG_RUNNING, &ep->flags); + ep->use_count--; + deactivate_urbs(ep, 0, 0); + return -EPIPE; +} + +void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, + int force, int can_sleep, int wait) +{ + if (!ep) + return; + + if (snd_BUG_ON(ep->use_count == 0)) + return; + + if (snd_BUG_ON(!test_bit(EP_FLAG_ACTIVATED, &ep->flags))) + return; + + if (--ep->use_count == 0) { + deactivate_urbs(ep, force, can_sleep); + ep->data_subs = NULL; + ep->sync_slave = NULL; + ep->retire_data_urb = NULL; + ep->prepare_data_urb = NULL; + + if (wait) + wait_clear_urbs(ep); + } +} + +int snd_usb_endpoint_activate(struct snd_usb_endpoint *ep) +{ + if (ep->use_count != 0) + return 0; + + if (!ep->chip->shutdown && + !test_and_set_bit(EP_FLAG_ACTIVATED, &ep->flags)) { + int ret; + + ret = usb_set_interface(ep->chip->dev, ep->iface, ep->alt_idx); + if (ret < 0) { + snd_printk(KERN_ERR "%s() usb_set_interface() failed, ret = %d\n", + __func__, ret); + clear_bit(EP_FLAG_ACTIVATED, &ep->flags); + return ret; + } + + return 0; + } + + return -EBUSY; +} + +int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep) +{ + if (!ep) + return -EINVAL; + + if (ep->use_count != 0) + return 0; + + if (!ep->chip->shutdown && + test_and_clear_bit(EP_FLAG_ACTIVATED, &ep->flags)) { + int ret; + + ret = usb_set_interface(ep->chip->dev, ep->iface, 0); + if (ret < 0) { + snd_printk(KERN_ERR "%s(): usb_set_interface() failed, ret = %d\n", + __func__, ret); + return ret; + } + + return 0; + } + + return -EBUSY; +} + +void snd_usb_endpoint_free(struct list_head *head) +{ + struct snd_usb_endpoint *ep; + + ep = list_entry(head, struct snd_usb_endpoint, list); + release_urbs(ep, 1); + kfree(ep); +} + +/* + * process after playback sync complete + * + * Full speed devices report feedback values in 10.14 format as samples per + * frame, high speed devices in 16.16 format as samples per microframe. + * Because the Audio Class 1 spec was written before USB 2.0, many high speed + * devices use a wrong interpretation, some others use an entirely different + * format. Therefore, we cannot predict what format any particular device uses + * and must detect it automatically. + */ +void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, + struct snd_usb_endpoint *sender, + const struct urb *urb) +{ + int shift; + unsigned int f; + unsigned long flags; + + snd_BUG_ON(ep == sender); + + if (snd_usb_endpoint_implict_feedback_sink(ep) && + ep->use_count != 0) { + + /* implicit feedback case */ + int i, bytes = 0; + struct snd_urb_ctx *in_ctx; + struct snd_usb_packet_info *out_packet; + + in_ctx = urb->context; + + /* Count overall packet size */ + for (i = 0; i < in_ctx->packets; i++) + if (urb->iso_frame_desc[i].status == 0) + bytes += urb->iso_frame_desc[i].actual_length; + + /* + * skip empty packets. At least M-Audio's Fast Track Ultra stops + * streaming once it received a 0-byte OUT URB + */ + if (bytes == 0) + return; + + spin_lock_irqsave(&ep->lock, flags); + out_packet = ep->next_packet + ep->next_packet_write_pos; + + /* + * Iterate through the inbound packet and prepare the lengths + * for the output packet. The OUT packet we are about to send + * will have the same amount of payload than the IN packet we + * just received. + */ + + out_packet->packets = in_ctx->packets; + for (i = 0; i < in_ctx->packets; i++) { + if (urb->iso_frame_desc[i].status == 0) + out_packet->packet_size[i] = + urb->iso_frame_desc[i].actual_length / ep->stride; + else + out_packet->packet_size[i] = 0; + } + + ep->next_packet_write_pos++; + ep->next_packet_write_pos %= MAX_URBS; + spin_unlock_irqrestore(&ep->lock, flags); + queue_pending_output_urbs(ep); + + return; + } + + /* parse sync endpoint packet */ + + if (urb->iso_frame_desc[0].status != 0 || + urb->iso_frame_desc[0].actual_length < 3) + return; + + f = le32_to_cpup(urb->transfer_buffer); + if (urb->iso_frame_desc[0].actual_length == 3) + f &= 0x00ffffff; + else + f &= 0x0fffffff; + + if (f == 0) + return; + + if (unlikely(ep->freqshift == INT_MIN)) { + /* + * The first time we see a feedback value, determine its format + * by shifting it left or right until it matches the nominal + * frequency value. This assumes that the feedback does not + * differ from the nominal value more than +50% or -25%. + */ + shift = 0; + while (f < ep->freqn - ep->freqn / 4) { + f <<= 1; + shift++; + } + while (f > ep->freqn + ep->freqn / 2) { + f >>= 1; + shift--; + } + ep->freqshift = shift; + } + else if (ep->freqshift >= 0) + f <<= ep->freqshift; + else + f >>= -ep->freqshift; + + if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) { + /* + * If the frequency looks valid, set it. + * This value is referred to in prepare_playback_urb(). + */ + spin_lock_irqsave(&ep->lock, flags); + ep->freqm = f; + spin_unlock_irqrestore(&ep->lock, flags); + } else { + /* + * Out of range; maybe the shift value is wrong. + * Reset it so that we autodetect again the next time. + */ + ep->freqshift = INT_MIN; + } +} + diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h index 88eb63a..9f083d7 100644 --- a/sound/usb/endpoint.h +++ b/sound/usb/endpoint.h @@ -18,4 +18,30 @@ int snd_usb_substream_prepare(struct snd_usb_substream *subs, int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substream, int cmd); int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream, int cmd);

+ +#define SND_USB_ENDPOINT_TYPE_DATA 0 +#define SND_USB_ENDPOINT_TYPE_SYNC 1 + +struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip, + struct usb_host_interface *alts, + int ep_num, int direction, int type); + +int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, + struct snd_pcm_hw_params *hw_params, + struct audioformat *fmt, + struct snd_usb_endpoint *sync_ep); + +int snd_usb_endpoint_start(struct snd_usb_endpoint *ep); +void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, + int force, int can_sleep, int wait); +int snd_usb_endpoint_activate(struct snd_usb_endpoint *ep); +int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep); +void snd_usb_endpoint_free(struct list_head *head); + +int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep); + +void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, + struct snd_usb_endpoint *sender, + const struct urb *urb); + #endif /* __USBAUDIO_ENDPOINT_H */ diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h index a16c21d..b8233eb 100644 --- a/sound/usb/usbaudio.h +++ b/sound/usb/usbaudio.h @@ -47,6 +47,7 @@ struct snd_usb_audio { int num_suspended_intf;

struct list_head pcm_list; /* list of pcm streams */ + struct list_head ep_list; /* list of audio-related endpoints */ int pcm_devs;

struct list_head midi_list; /* list of midi interfaces */

Signed-off-by: Daniel Mack zonque@gmail.com --- sound/usb/endpoint.c | 850 +------------------------------------------------- sound/usb/endpoint.h | 15 - 2 files changed, 6 insertions(+), 859 deletions(-)

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index c7f9bcf..81f19f8 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -54,727 +54,16 @@ static inline unsigned get_usb_high_speed_rate(unsigned int rate) }

/* - * unlink active urbs. - */ -static int deactivate_urbs_old(struct snd_usb_substream *subs, int force, int can_sleep) -{ - struct snd_usb_audio *chip = subs->stream->chip; - unsigned int i; - int async; - - subs->running = 0; - - if (!force && subs->stream->chip->shutdown) /* to be sure... */ - return -EBADFD; - - async = !can_sleep && chip->async_unlink; - - if (!async && in_interrupt()) - return 0; - - for (i = 0; i < subs->nurbs; i++) { - if (test_bit(i, &subs->active_mask)) { - if (!test_and_set_bit(i, &subs->unlink_mask)) { - struct urb *u = subs->dataurb[i].urb; - if (async) - usb_unlink_urb(u); - else - usb_kill_urb(u); - } - } - } - if (subs->syncpipe) { - for (i = 0; i < SYNC_URBS; i++) { - if (test_bit(i+16, &subs->active_mask)) { - if (!test_and_set_bit(i+16, &subs->unlink_mask)) { - struct urb *u = subs->syncurb[i].urb; - if (async) - usb_unlink_urb(u); - else - usb_kill_urb(u); - } - } - } - } - return 0; -} - - -/* * release a urb data */ static void release_urb_ctx(struct snd_urb_ctx *u) { - if (u->urb) { - if (u->buffer_size) - usb_free_coherent(u->subs->dev, u->buffer_size, - u->urb->transfer_buffer, - u->urb->transfer_dma); - usb_free_urb(u->urb); - u->urb = NULL; - } -} - -/* - * wait until all urbs are processed. - */ -static int wait_clear_urbs_old(struct snd_usb_substream *subs) -{ - unsigned long end_time = jiffies + msecs_to_jiffies(1000); - unsigned int i; - int alive; - - do { - alive = 0; - for (i = 0; i < subs->nurbs; i++) { - if (test_bit(i, &subs->active_mask)) - alive++; - } - if (subs->syncpipe) { - for (i = 0; i < SYNC_URBS; i++) { - if (test_bit(i + 16, &subs->active_mask)) - alive++; - } - } - if (! alive) - break; - schedule_timeout_uninterruptible(1); - } while (time_before(jiffies, end_time)); - if (alive) - snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive); - return 0; -} - -/* - * release a substream - */ -void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force) -{ - int i; - - /* stop urbs (to be sure) */ - deactivate_urbs_old(subs, force, 1); - wait_clear_urbs_old(subs); - - for (i = 0; i < MAX_URBS; i++) - release_urb_ctx(&subs->dataurb[i]); - for (i = 0; i < SYNC_URBS; i++) - release_urb_ctx(&subs->syncurb[i]); - usb_free_coherent(subs->dev, SYNC_URBS * 4, - subs->syncbuf, subs->sync_dma); - subs->syncbuf = NULL; - subs->nurbs = 0; -} - -/* - * complete callback from data urb - */ -static void snd_complete_urb_old(struct urb *urb) -{ - struct snd_urb_ctx *ctx = urb->context; - struct snd_usb_substream *subs = ctx->subs; - struct snd_pcm_substream *substream = ctx->subs->pcm_substream; - int err = 0; - - if ((subs->running && subs->ops.retire(subs, substream->runtime, urb)) || - !subs->running || /* can be stopped during retire callback */ - (err = subs->ops.prepare(subs, substream->runtime, urb)) < 0 || - (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) { - clear_bit(ctx->index, &subs->active_mask); - if (err < 0) { - snd_printd(KERN_ERR "cannot submit urb (err = %d)\n", err); - snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN); - } - } -} - - -/* - * complete callback from sync urb - */ -static void snd_complete_sync_urb(struct urb *urb) -{ - struct snd_urb_ctx *ctx = urb->context; - struct snd_usb_substream *subs = ctx->subs; - struct snd_pcm_substream *substream = ctx->subs->pcm_substream; - int err = 0; - - if ((subs->running && subs->ops.retire_sync(subs, substream->runtime, urb)) || - !subs->running || /* can be stopped during retire callback */ - (err = subs->ops.prepare_sync(subs, substream->runtime, urb)) < 0 || - (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) { - clear_bit(ctx->index + 16, &subs->active_mask); - if (err < 0) { - snd_printd(KERN_ERR "cannot submit sync urb (err = %d)\n", err); - snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN); - } - } -} - - -/* - * initialize a substream for plaback/capture - */ -int snd_usb_init_substream_urbs(struct snd_usb_substream *subs, - unsigned int period_bytes, - unsigned int rate, - unsigned int frame_bits) -{ - unsigned int maxsize, i; - int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK; - unsigned int urb_packs, total_packs, packs_per_ms; - struct snd_usb_audio *chip = subs->stream->chip; - - /* calculate the frequency in 16.16 format */ - if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL) - subs->freqn = get_usb_full_speed_rate(rate); - else - subs->freqn = get_usb_high_speed_rate(rate); - subs->freqm = subs->freqn; - subs->freqshift = INT_MIN; - /* calculate max. frequency */ - if (subs->maxpacksize) { - /* whatever fits into a max. size packet */ - maxsize = subs->maxpacksize; - subs->freqmax = (maxsize / (frame_bits >> 3)) - << (16 - subs->datainterval); - } else { - /* no max. packet size: just take 25% higher than nominal */ - subs->freqmax = subs->freqn + (subs->freqn >> 2); - maxsize = ((subs->freqmax + 0xffff) * (frame_bits >> 3)) - >> (16 - subs->datainterval); - } - subs->phase = 0; - - if (subs->fill_max) - subs->curpacksize = subs->maxpacksize; - else - subs->curpacksize = maxsize; - - if (snd_usb_get_speed(subs->dev) != USB_SPEED_FULL) - packs_per_ms = 8 >> subs->datainterval; - else - packs_per_ms = 1; - - if (is_playback) { - urb_packs = max(chip->nrpacks, 1); - urb_packs = min(urb_packs, (unsigned int)MAX_PACKS); - } else - urb_packs = 1; - urb_packs *= packs_per_ms; - if (subs->syncpipe) - urb_packs = min(urb_packs, 1U << subs->syncinterval); - - /* decide how many packets to be used */ - if (is_playback) { - unsigned int minsize, maxpacks; - /* determine how small a packet can be */ - minsize = (subs->freqn >> (16 - subs->datainterval)) - * (frame_bits >> 3); - /* with sync from device, assume it can be 12% lower */ - if (subs->syncpipe) - minsize -= minsize >> 3; - minsize = max(minsize, 1u); - total_packs = (period_bytes + minsize - 1) / minsize; - /* we need at least two URBs for queueing */ - if (total_packs < 2) { - total_packs = 2; - } else { - /* and we don't want too long a queue either */ - maxpacks = max(MAX_QUEUE * packs_per_ms, urb_packs * 2); - total_packs = min(total_packs, maxpacks); - } - } else { - while (urb_packs > 1 && urb_packs * maxsize >= period_bytes) - urb_packs >>= 1; - total_packs = MAX_URBS * urb_packs; - } - subs->nurbs = (total_packs + urb_packs - 1) / urb_packs; - if (subs->nurbs > MAX_URBS) { - /* too much... */ - subs->nurbs = MAX_URBS; - total_packs = MAX_URBS * urb_packs; - } else if (subs->nurbs < 2) { - /* too little - we need at least two packets - * to ensure contiguous playback/capture - */ - subs->nurbs = 2; - } - - /* allocate and initialize data urbs */ - for (i = 0; i < subs->nurbs; i++) { - struct snd_urb_ctx *u = &subs->dataurb[i]; - u->index = i; - u->subs = subs; - u->packets = (i + 1) * total_packs / subs->nurbs - - i * total_packs / subs->nurbs; - u->buffer_size = maxsize * u->packets; - if (subs->fmt_type == UAC_FORMAT_TYPE_II) - u->packets++; /* for transfer delimiter */ - u->urb = usb_alloc_urb(u->packets, GFP_KERNEL); - if (!u->urb) - goto out_of_memory; - u->urb->transfer_buffer = - usb_alloc_coherent(subs->dev, u->buffer_size, - GFP_KERNEL, &u->urb->transfer_dma); - if (!u->urb->transfer_buffer) - goto out_of_memory; - u->urb->pipe = subs->datapipe; - u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP; - u->urb->interval = 1 << subs->datainterval; - u->urb->context = u; - u->urb->complete = snd_complete_urb_old; - } - - if (subs->syncpipe) { - /* allocate and initialize sync urbs */ - subs->syncbuf = usb_alloc_coherent(subs->dev, SYNC_URBS * 4, - GFP_KERNEL, &subs->sync_dma); - if (!subs->syncbuf) - goto out_of_memory; - for (i = 0; i < SYNC_URBS; i++) { - struct snd_urb_ctx *u = &subs->syncurb[i]; - u->index = i; - u->subs = subs; - u->packets = 1; - u->urb = usb_alloc_urb(1, GFP_KERNEL); - if (!u->urb) - goto out_of_memory; - u->urb->transfer_buffer = subs->syncbuf + i * 4; - u->urb->transfer_dma = subs->sync_dma + i * 4; - u->urb->transfer_buffer_length = 4; - u->urb->pipe = subs->syncpipe; - u->urb->transfer_flags = URB_ISO_ASAP | - URB_NO_TRANSFER_DMA_MAP; - u->urb->number_of_packets = 1; - u->urb->interval = 1 << subs->syncinterval; - u->urb->context = u; - u->urb->complete = snd_complete_sync_urb; - } - } - return 0; - -out_of_memory: - snd_usb_release_substream_urbs(subs, 0); - return -ENOMEM; -} - -/* - * prepare urb for full speed capture sync pipe - * - * fill the length and offset of each urb descriptor. - * the fixed 10.14 frequency is passed through the pipe. - */ -static int prepare_capture_sync_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - unsigned char *cp = urb->transfer_buffer; - struct snd_urb_ctx *ctx = urb->context; - - urb->dev = ctx->subs->dev; /* we need to set this at each time */ - urb->iso_frame_desc[0].length = 3; - urb->iso_frame_desc[0].offset = 0; - cp[0] = subs->freqn >> 2; - cp[1] = subs->freqn >> 10; - cp[2] = subs->freqn >> 18; - return 0; -} - -/* - * prepare urb for high speed capture sync pipe - * - * fill the length and offset of each urb descriptor. - * the fixed 12.13 frequency is passed as 16.16 through the pipe. - */ -static int prepare_capture_sync_urb_hs(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - unsigned char *cp = urb->transfer_buffer; - struct snd_urb_ctx *ctx = urb->context; - - urb->dev = ctx->subs->dev; /* we need to set this at each time */ - urb->iso_frame_desc[0].length = 4; - urb->iso_frame_desc[0].offset = 0; - cp[0] = subs->freqn; - cp[1] = subs->freqn >> 8; - cp[2] = subs->freqn >> 16; - cp[3] = subs->freqn >> 24; - return 0; -} - -/* - * process after capture sync complete - * - nothing to do - */ -static int retire_capture_sync_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - return 0; -} - -/* - * prepare urb for capture data pipe - * - * fill the offset and length of each descriptor. - * - * we use a temporary buffer to write the captured data. - * since the length of written data is determined by host, we cannot - * write onto the pcm buffer directly... the data is thus copied - * later at complete callback to the global buffer. - */ -static int prepare_capture_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - int i, offs; - struct snd_urb_ctx *ctx = urb->context; - - offs = 0; - urb->dev = ctx->subs->dev; /* we need to set this at each time */ - for (i = 0; i < ctx->packets; i++) { - urb->iso_frame_desc[i].offset = offs; - urb->iso_frame_desc[i].length = subs->curpacksize; - offs += subs->curpacksize; - } - urb->transfer_buffer_length = offs; - urb->number_of_packets = ctx->packets; - return 0; -} - -/* - * process after capture complete - * - * copy the data from each desctiptor to the pcm buffer, and - * update the current position. - */ -static int retire_capture_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - unsigned long flags; - unsigned char *cp; - int i; - unsigned int stride, frames, bytes, oldptr; - int period_elapsed = 0; - - stride = runtime->frame_bits >> 3; - - for (i = 0; i < urb->number_of_packets; i++) { - cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset; - if (urb->iso_frame_desc[i].status && printk_ratelimit()) { - snd_printdd("frame %d active: %d\n", i, urb->iso_frame_desc[i].status); - // continue; - } - bytes = urb->iso_frame_desc[i].actual_length; - frames = bytes / stride; - if (!subs->txfr_quirk) - bytes = frames * stride; - if (bytes % (runtime->sample_bits >> 3) != 0) { -#ifdef CONFIG_SND_DEBUG_VERBOSE - int oldbytes = bytes; -#endif - bytes = frames * stride; - snd_printdd(KERN_ERR "Corrected urb data len. %d->%d\n", - oldbytes, bytes); - } - /* update the current pointer */ - spin_lock_irqsave(&subs->lock, flags); - oldptr = subs->hwptr_done; - subs->hwptr_done += bytes; - if (subs->hwptr_done >= runtime->buffer_size * stride) - subs->hwptr_done -= runtime->buffer_size * stride; - frames = (bytes + (oldptr % stride)) / stride; - subs->transfer_done += frames; - if (subs->transfer_done >= runtime->period_size) { - subs->transfer_done -= runtime->period_size; - period_elapsed = 1; - } - spin_unlock_irqrestore(&subs->lock, flags); - /* copy a data chunk */ - if (oldptr + bytes > runtime->buffer_size * stride) { - unsigned int bytes1 = - runtime->buffer_size * stride - oldptr; - memcpy(runtime->dma_area + oldptr, cp, bytes1); - memcpy(runtime->dma_area, cp + bytes1, bytes - bytes1); - } else { - memcpy(runtime->dma_area + oldptr, cp, bytes); - } - } - if (period_elapsed) - snd_pcm_period_elapsed(subs->pcm_substream); - return 0; -} - -/* - * Process after capture complete when paused. Nothing to do. - */ -static int retire_paused_capture_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - return 0; -} - - -/* - * prepare urb for playback sync pipe - * - * set up the offset and length to receive the current frequency. - */ -static int prepare_playback_sync_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - struct snd_urb_ctx *ctx = urb->context; - - urb->dev = ctx->subs->dev; /* we need to set this at each time */ - urb->iso_frame_desc[0].length = min(4u, ctx->subs->syncmaxsize); - urb->iso_frame_desc[0].offset = 0; - return 0; -} - -/* - * process after playback sync complete - * - * Full speed devices report feedback values in 10.14 format as samples per - * frame, high speed devices in 16.16 format as samples per microframe. - * Because the Audio Class 1 spec was written before USB 2.0, many high speed - * devices use a wrong interpretation, some others use an entirely different - * format. Therefore, we cannot predict what format any particular device uses - * and must detect it automatically. - */ -static int retire_playback_sync_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - unsigned int f; - int shift; - unsigned long flags; - - if (urb->iso_frame_desc[0].status != 0 || - urb->iso_frame_desc[0].actual_length < 3) - return 0; - - f = le32_to_cpup(urb->transfer_buffer); - if (urb->iso_frame_desc[0].actual_length == 3) - f &= 0x00ffffff; - else - f &= 0x0fffffff; - if (f == 0) - return 0; - - if (unlikely(subs->freqshift == INT_MIN)) { - /* - * The first time we see a feedback value, determine its format - * by shifting it left or right until it matches the nominal - * frequency value. This assumes that the feedback does not - * differ from the nominal value more than +50% or -25%. - */ - shift = 0; - while (f < subs->freqn - subs->freqn / 4) { - f <<= 1; - shift++; - } - while (f > subs->freqn + subs->freqn / 2) { - f >>= 1; - shift--; - } - subs->freqshift = shift; - } - else if (subs->freqshift >= 0) - f <<= subs->freqshift; - else - f >>= -subs->freqshift; - - if (likely(f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax)) { - /* - * If the frequency looks valid, set it. - * This value is referred to in prepare_playback_urb(). - */ - spin_lock_irqsave(&subs->lock, flags); - subs->freqm = f; - spin_unlock_irqrestore(&subs->lock, flags); - } else { - /* - * Out of range; maybe the shift value is wrong. - * Reset it so that we autodetect again the next time. - */ - subs->freqshift = INT_MIN; - } - - return 0; -} - -/* determine the number of frames in the next packet */ -static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs) -{ - if (subs->fill_max) - return subs->maxframesize; - else { - subs->phase = (subs->phase & 0xffff) - + (subs->freqm << subs->datainterval); - return min(subs->phase >> 16, subs->maxframesize); - } -} - -/* - * Prepare urb for streaming before playback starts or when paused. - * - * We don't have any data, so we send silence. - */ -static int prepare_nodata_playback_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - unsigned int i, offs, counts; - struct snd_urb_ctx *ctx = urb->context; - int stride = runtime->frame_bits >> 3; - - offs = 0; - urb->dev = ctx->subs->dev; - for (i = 0; i < ctx->packets; ++i) { - counts = snd_usb_audio_next_packet_size(subs); - urb->iso_frame_desc[i].offset = offs * stride; - urb->iso_frame_desc[i].length = counts * stride; - offs += counts; - } - urb->number_of_packets = ctx->packets; - urb->transfer_buffer_length = offs * stride; - memset(urb->transfer_buffer, - runtime->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0, - offs * stride); - return 0; -} - -/* - * prepare urb for playback data pipe - * - * Since a URB can handle only a single linear buffer, we must use double - * buffering when the data to be transferred overflows the buffer boundary. - * To avoid inconsistencies when updating hwptr_done, we use double buffering - * for all URBs. - */ -static int prepare_playback_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - int i, stride; - unsigned int counts, frames, bytes; - unsigned long flags; - int period_elapsed = 0; - struct snd_urb_ctx *ctx = urb->context; - - stride = runtime->frame_bits >> 3; - - frames = 0; - urb->dev = ctx->subs->dev; /* we need to set this at each time */ - urb->number_of_packets = 0; - spin_lock_irqsave(&subs->lock, flags); - for (i = 0; i < ctx->packets; i++) { - counts = snd_usb_audio_next_packet_size(subs); - /* set up descriptor */ - urb->iso_frame_desc[i].offset = frames * stride; - urb->iso_frame_desc[i].length = counts * stride; - frames += counts; - urb->number_of_packets++; - subs->transfer_done += counts; - if (subs->transfer_done >= runtime->period_size) { - subs->transfer_done -= runtime->period_size; - period_elapsed = 1; - if (subs->fmt_type == UAC_FORMAT_TYPE_II) { - if (subs->transfer_done > 0) { - /* FIXME: fill-max mode is not - * supported yet */ - frames -= subs->transfer_done; - counts -= subs->transfer_done; - urb->iso_frame_desc[i].length = - counts * stride; - subs->transfer_done = 0; - } - i++; - if (i < ctx->packets) { - /* add a transfer delimiter */ - urb->iso_frame_desc[i].offset = - frames * stride; - urb->iso_frame_desc[i].length = 0; - urb->number_of_packets++; - } - break; - } - } - if (period_elapsed) /* finish at the period boundary */ - break; - } - bytes = frames * stride; - if (subs->hwptr_done + bytes > runtime->buffer_size * stride) { - /* err, the transferred area goes over buffer boundary. */ - unsigned int bytes1 = - runtime->buffer_size * stride - subs->hwptr_done; - memcpy(urb->transfer_buffer, - runtime->dma_area + subs->hwptr_done, bytes1); - memcpy(urb->transfer_buffer + bytes1, - runtime->dma_area, bytes - bytes1); - } else { - memcpy(urb->transfer_buffer, - runtime->dma_area + subs->hwptr_done, bytes); - } - subs->hwptr_done += bytes; - if (subs->hwptr_done >= runtime->buffer_size * stride) - subs->hwptr_done -= runtime->buffer_size * stride; - - /* update delay with exact number of samples queued */ - runtime->delay = subs->last_delay; - runtime->delay += frames; - subs->last_delay = runtime->delay; - - /* realign last_frame_number */ - subs->last_frame_number = usb_get_current_frame_number(subs->dev); - subs->last_frame_number &= 0xFF; /* keep 8 LSBs */ - - spin_unlock_irqrestore(&subs->lock, flags); - urb->transfer_buffer_length = bytes; - if (period_elapsed) - snd_pcm_period_elapsed(subs->pcm_substream); - return 0; -} - -/* - * process after playback data complete - * - decrease the delay count again - */ -static int retire_playback_urb(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime, - struct urb *urb) -{ - unsigned long flags; - int stride = runtime->frame_bits >> 3; - int processed = urb->transfer_buffer_length / stride; - int est_delay; - - spin_lock_irqsave(&subs->lock, flags); - - est_delay = snd_usb_pcm_delay(subs, runtime->rate); - /* update delay with exact number of samples played */ - if (processed > subs->last_delay) - subs->last_delay = 0; - else - subs->last_delay -= processed; - runtime->delay = subs->last_delay; - - /* - * Report when delay estimate is off by more than 2ms. - * The error should be lower than 2ms since the estimate relies - * on two reads of a counter updated every ms. - */ - if (abs(est_delay - subs->last_delay) * 1000 > runtime->rate * 2) - snd_printk(KERN_DEBUG "delay: estimated %d, actual %d\n", - est_delay, subs->last_delay); - - spin_unlock_irqrestore(&subs->lock, flags); - return 0; + if (u->buffer_size) + usb_free_coherent(u->ep->chip->dev, u->buffer_size, + u->urb->transfer_buffer, + u->urb->transfer_dma); + usb_free_urb(u->urb); + u->urb = NULL; }

static const char *usb_error_string(int err) @@ -802,133 +91,6 @@ static const char *usb_error_string(int err) } }

-/* - * set up and start data/sync urbs - */ -static int start_urbs(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime) -{ - unsigned int i; - int err; - - if (subs->stream->chip->shutdown) - return -EBADFD; - - for (i = 0; i < subs->nurbs; i++) { - if (snd_BUG_ON(!subs->dataurb[i].urb)) - return -EINVAL; - if (subs->ops.prepare(subs, runtime, subs->dataurb[i].urb) < 0) { - snd_printk(KERN_ERR "cannot prepare datapipe for urb %d\n", i); - goto __error; - } - } - if (subs->syncpipe) { - for (i = 0; i < SYNC_URBS; i++) { - if (snd_BUG_ON(!subs->syncurb[i].urb)) - return -EINVAL; - if (subs->ops.prepare_sync(subs, runtime, subs->syncurb[i].urb) < 0) { - snd_printk(KERN_ERR "cannot prepare syncpipe for urb %d\n", i); - goto __error; - } - } - } - - subs->active_mask = 0; - subs->unlink_mask = 0; - subs->running = 1; - for (i = 0; i < subs->nurbs; i++) { - err = usb_submit_urb(subs->dataurb[i].urb, GFP_ATOMIC); - if (err < 0) { - snd_printk(KERN_ERR "cannot submit datapipe " - "for urb %d, error %d: %s\n", - i, err, usb_error_string(err)); - goto __error; - } - set_bit(i, &subs->active_mask); - } - if (subs->syncpipe) { - for (i = 0; i < SYNC_URBS; i++) { - err = usb_submit_urb(subs->syncurb[i].urb, GFP_ATOMIC); - if (err < 0) { - snd_printk(KERN_ERR "cannot submit syncpipe " - "for urb %d, error %d: %s\n", - i, err, usb_error_string(err)); - goto __error; - } - set_bit(i + 16, &subs->active_mask); - } - } - return 0; - - __error: - // snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN); - deactivate_urbs_old(subs, 0, 0); - return -EPIPE; -} - - -/* - */ -static struct snd_urb_ops audio_urb_ops[2] = { - { - .prepare = prepare_nodata_playback_urb, - .retire = retire_playback_urb, - .prepare_sync = prepare_playback_sync_urb, - .retire_sync = retire_playback_sync_urb, - }, - { - .prepare = prepare_capture_urb, - .retire = retire_capture_urb, - .prepare_sync = prepare_capture_sync_urb, - .retire_sync = retire_capture_sync_urb, - }, -}; - -/* - * initialize the substream instance. - */ - -void snd_usb_init_substream(struct snd_usb_stream *as, - int stream, struct audioformat *fp) -{ - struct snd_usb_substream *subs = &as->substream[stream]; - - INIT_LIST_HEAD(&subs->fmt_list); - spin_lock_init(&subs->lock); - - subs->stream = as; - subs->direction = stream; - subs->dev = as->chip->dev; - subs->txfr_quirk = as->chip->txfr_quirk; - subs->ops = audio_urb_ops[stream]; - if (snd_usb_get_speed(subs->dev) >= USB_SPEED_HIGH) - subs->ops.prepare_sync = prepare_capture_sync_urb_hs; - - snd_usb_set_pcm_ops(as->pcm, stream); - - list_add_tail(&fp->list, &subs->fmt_list); - subs->formats |= fp->formats; - subs->endpoint = fp->endpoint; - subs->num_formats++; - subs->fmt_type = fp->fmt_type; -} - -int snd_usb_substream_prepare(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime) -{ - /* clear urbs (to be sure) */ - deactivate_urbs_old(subs, 0, 1); - wait_clear_urbs_old(subs); - - /* for playback, submit the URBs now; otherwise, the first hwptr_done - * updates for all URBs would happen at the same time when starting */ - if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) { - subs->ops.prepare = prepare_nodata_playback_urb; - return start_urbs(subs, runtime); - } - - return 0; -} - int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep) { return ep->sync_master && diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h index e540768..ee2723f 100644 --- a/sound/usb/endpoint.h +++ b/sound/usb/endpoint.h @@ -1,21 +1,6 @@ #ifndef __USBAUDIO_ENDPOINT_H #define __USBAUDIO_ENDPOINT_H

-void snd_usb_init_substream(struct snd_usb_stream *as, - int stream, - struct audioformat *fp); - -int snd_usb_init_substream_urbs(struct snd_usb_substream *subs, - unsigned int period_bytes, - unsigned int rate, - unsigned int frame_bits); - -void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force); - -int snd_usb_substream_prepare(struct snd_usb_substream *subs, - struct snd_pcm_runtime *runtime); - - #define SND_USB_ENDPOINT_TYPE_DATA 0 #define SND_USB_ENDPOINT_TYPE_SYNC 1

Document the new streaming code and some of the functions so that contributers can catch up easier.

Signed-off-by: Daniel Mack zonque@gmail.com --- sound/usb/endpoint.c | 182 +++++++++++++++++++++++++++++++++++++++++++++++--- 1 files changed, 171 insertions(+), 11 deletions(-)

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 81f19f8..5cfad6d 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -36,6 +36,32 @@ #define EP_FLAG_RUNNING 1

/* + * snd_usb_endpoint is a model that abstracts everything related to an + * USB endpoint and its streaming. + * + * There are functions to activate and deactivate the streaming URBs and + * optinal callbacks to let the pcm logic handle the actual content of the + * packets for playback and record. Thus, the bus streaming and the audio + * handlers are fully decoupled. + * + * There are two different types of endpoints in for audio applications. + * + * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both + * inbound and outbound traffic. + * + * SND_USB_ENDPOINT_TYPE_SYNC are for inbound traffic only and expect the + * payload to carry Q16.16 formatted sync information (3 or 4 bytes). + * + * Each endpoint has to be configured (by calling + * snd_usb_endpoint_set_params()) before it can be used. + * + * The model incorporates a reference counting, so that multiple users + * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and + * only the first user will effectively start the URBs, and only the last + * one will tear them down again. + */ + +/* * convert a sampling rate into our full speed format (fs/1000 in Q16.16) * this will overflow at approx 524 kHz */ @@ -91,6 +117,14 @@ static const char *usb_error_string(int err) } }

+/** + * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type + * + * @ep: The endpoint + * + * Determine whether an endpoint is driven by an implicit feedback + * data endpoint source. + */ int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep) { return ep->sync_master && @@ -99,7 +133,13 @@ int snd_usb_endpoint_implict_feedback_sink(struct snd_usb_endpoint *ep) usb_pipeout(ep->pipe); }

-/* determine the number of frames in the next packet */ +/* + * For streaming based on information derived from sync endpoints, + * prepare_outbound_urb_sizes() will call next_packet_size() to + * determine the number of samples to be sent in the next packet. + * + * For implicit feedback, next_packet_size() is unused. + */ static int next_packet_size(struct snd_usb_endpoint *ep) { unsigned long flags; @@ -237,6 +277,19 @@ static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep, } }

+/* + * Send output urbs that have been prepared previously. Urbs are dequeued + * from ep->ready_playback_urbs and in case there there aren't any available + * or there are no packets that have been prepared, this function does + * nothing. + * + * The reason why the functionality of sending and preparing urbs is separated + * is that host controllers don't guarantee an ordering in returing inbound + * and outbound packets to their submitters. + * + * This function is only used for implicit feedback endpoints. For endpoints + * driven by sync endpoints, urbs are submitted from their completion handler. + */ static void queue_pending_output_urbs(struct snd_usb_endpoint *ep) { while (test_bit(EP_FLAG_RUNNING, &ep->flags)) { @@ -270,6 +323,7 @@ static void queue_pending_output_urbs(struct snd_usb_endpoint *ep) for (i = 0; i < packet->packets; i++) ctx->packet_size[i] = packet->packet_size[i];

+ /* call the data handler to fill in playback data */ prepare_outbound_urb(ep, ctx);

err = usb_submit_urb(ctx->urb, GFP_ATOMIC); @@ -336,6 +390,22 @@ exit_clear: clear_bit(ctx->index, &ep->active_mask); }

+/** + * snd_usb_add_endpoint: Add an endpoint to an audio chip + * + * @chip: The chip + * @alts: The USB host interface + * @ep_num: The number of the endpoint to use + * @direction: SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE + * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC + * + * If the requested endpoint has not been added to the given chip before, + * a new instance is created. Otherwise, a pointer to the previoulsy + * created instance is returned. In case of any error, NULL is returned. + * + * New endpoints will be added to chip->ep_list and must be freed by + * calling snd_usb_endpoint_free(). + */ struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip, struct usb_host_interface *alts, int ep_num, int direction, int type) @@ -506,6 +576,9 @@ static void release_urbs(struct snd_usb_endpoint *ep, int force) ep->nurbs = 0; }

+/* + * configure a data endpoint + */ static int data_ep_set_params(struct snd_usb_endpoint *ep, struct snd_pcm_hw_params *hw_params, struct audioformat *fmt, @@ -629,6 +702,9 @@ out_of_memory: return -ENOMEM; }

+/* + * configure a sync endpoint + */ static int sync_ep_set_params(struct snd_usb_endpoint *ep, struct snd_pcm_hw_params *hw_params, struct audioformat *fmt) @@ -669,6 +745,15 @@ out_of_memory: return -ENOMEM; }

+/** + * snd_usb_endpoint_set_params: configure an snd_endpoint + * + * @ep: the endpoint to configure + * + * Determine the number of of URBs to be used on this endpoint. + * An endpoint must be configured before it can be started. + * An endpoint that is already running can not be reconfigured. + */ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, struct snd_pcm_hw_params *hw_params, struct audioformat *fmt, @@ -717,6 +802,19 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, return err; }

+/** + * snd_usb_endpoint_start: start an snd_usb_endpoint + * + * @ep: the endpoint to start + * + * A call to this function will increment the use count of the endpoint. + * In case this not already running, the URBs for this endpoint will be + * submitted. Otherwise, this function does nothing. + * + * Must be balanced to calls of snd_usb_endpoint_stop(). + * + * Returns an error if the URB submission failed, 0 in all other cases. + */ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep) { int err; @@ -788,6 +886,17 @@ __error: return -EPIPE; }

+/** + * snd_usb_endpoint_stop: stop an snd_usb_endpoint + * + * @ep: the endpoint to stop (may be NULL) + * + * A call to this function will decrement the use count of the endpoint. + * In case the last user has requested the endpoint stop, the URBs will + * actually deactivated. + * + * Must be balanced to calls of snd_usb_endpoint_start(). + */ void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, int force, int can_sleep, int wait) { @@ -812,6 +921,19 @@ void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, } }

+/** + * snd_usb_endpoint_activate: activate an snd_usb_endpoint + * + * @ep: the endpoint to activate + * + * If the endpoint is not currently in use, this functions will select the + * correct alternate interface setting for the interface of this endpoint. + * + * In case of any active users, this functions does nothing. + * + * Returns an error if usb_set_interface() failed, 0 in all other + * cases. + */ int snd_usb_endpoint_activate(struct snd_usb_endpoint *ep) { if (ep->use_count != 0) @@ -835,6 +957,19 @@ int snd_usb_endpoint_activate(struct snd_usb_endpoint *ep) return -EBUSY; }

+/** + * snd_usb_endpoint_deactivate: deactivate an snd_usb_endpoint + * + * @ep: the endpoint to deactivate + * + * If the endpoint is not currently in use, this functions will select the + * alternate interface setting 0 for the interface of this endpoint. + * + * In case of any active users, this functions does nothing. + * + * Returns an error if usb_set_interface() failed, 0 in all other + * cases. + */ int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep) { if (!ep) @@ -860,6 +995,13 @@ int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep) return -EBUSY; }

+/** snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint + * + * @ep: the list header of the endpoint to free + * + * This function does not care for the endpoint's use count but will tear + * down all the streaming URBs immediately and free all resources. + */ void snd_usb_endpoint_free(struct list_head *head) { struct snd_usb_endpoint *ep; @@ -869,15 +1011,15 @@ void snd_usb_endpoint_free(struct list_head *head) kfree(ep); }

-/* - * process after playback sync complete - * - * Full speed devices report feedback values in 10.14 format as samples per - * frame, high speed devices in 16.16 format as samples per microframe. - * Because the Audio Class 1 spec was written before USB 2.0, many high speed - * devices use a wrong interpretation, some others use an entirely different - * format. Therefore, we cannot predict what format any particular device uses - * and must detect it automatically. +/** + * snd_usb_handle_sync_urb: parse an USB sync packet + * + * @ep: the endpoint to handle the packet + * @sender: the sending endpoint + * @urb: the received packet + * + * This function is called from the context of an endpoint that received + * the packet and is used to let another endpoint object handle the payload. */ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, struct snd_usb_endpoint *sender, @@ -889,6 +1031,11 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,

snd_BUG_ON(ep == sender);

+ /* + * In case the endpoint is operating in implicit feedback mode, prepare + * and a new outbound URB that has the same layout as the received + * packet and add it to the list of pending urbs. + */ if (snd_usb_endpoint_implict_feedback_sink(ep) && ep->use_count != 0) {

@@ -938,7 +1085,20 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, return; }

- /* parse sync endpoint packet */ + /* + * process after playback sync complete + * + * Full speed devices report feedback values in 10.14 format as samples + * per frame, high speed devices in 16.16 format as samples per + * microframe. + * + * Because the Audio Class 1 spec was written before USB 2.0, many high + * speed devices use a wrong interpretation, some others use an + * entirely different format. + * + * Therefore, we cannot predict what format any particular device uses + * and must detect it automatically. + */

if (urb->iso_frame_desc[0].status != 0 || urb->iso_frame_desc[0].actual_length < 3)