[alsa-devel] [PATCH v4 10/15] ALSA: usb-audio: conditional concurrent usage of endpoint
Eldad Zack
eldad at fogrefinery.com
Sun Oct 6 22:31:15 CEST 2013
If the current endpoint is in use, check if the hardware parameters
match. If they do, allow the usage.
This also requires setting the parameters in case an data endpoint
is used as a synchornization source, and it is first set by its
sink endpoint.
Also check the data endpoint on the substream in the other direction.
If it is in use, the rate and format must match.
The channel count may differ - but the period bytes must match.
If the channel count is different, adjust the expected period bytes
by the ratio of the channel count.
Add the same check to hw_params, to prevent overwriting the
current params.
Clear the hardware parameters on hw_free only if the other endpoint
is not in use.
No change for sync endpoints (explicit feedback).
Signed-off-by: Eldad Zack <eldad at fogrefinery.com>
---
v2: added checking the data endpoint on the substream in the other
direction.
---
sound/usb/endpoint.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++----
sound/usb/endpoint.h | 9 +++++++-
sound/usb/pcm.c | 59 ++++++++++++++++++++++++++++++++++++++----------
3 files changed, 114 insertions(+), 17 deletions(-)
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index c90d065..6cb3137 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -753,6 +753,51 @@ out_of_memory:
return -ENOMEM;
}
+bool snd_usb_endpoint_may_set_params(struct snd_usb_substream *subs,
+ snd_pcm_format_t pcm_format,
+ unsigned int channels,
+ unsigned int period_bytes,
+ unsigned int rate)
+{
+ struct snd_usb_substream *other_subs =
+ &subs->stream->substream[subs->direction ^ 1];
+ struct snd_usb_endpoint *other_ep = other_subs->data_endpoint;
+
+ /* no associated substream */
+ if (!subs)
+ return true;
+
+ if (other_ep && other_ep->use_count != 0) {
+ int other_pb;
+ if (other_subs->pcm_format != pcm_format ||
+ other_subs->cur_rate != rate)
+ return false;
+
+ other_pb = (other_subs->channels == channels ?
+ other_subs->period_bytes :
+ other_subs->period_bytes * channels / other_subs->channels);
+ if (other_pb != period_bytes)
+ return false;
+ }
+
+ /* data_endpoint not yet initialized */
+ if (!subs->data_endpoint)
+ return true;
+
+ if (subs->data_endpoint->use_count == 0)
+ return true;
+
+ if (subs->pcm_format != pcm_format ||
+ subs->channels != channels ||
+ subs->period_bytes != period_bytes ||
+ subs->cur_rate != rate)
+ return false;
+
+ snd_printdd(KERN_INFO "ep #%x in use, parameters match\n",
+ subs->data_endpoint->ep_num);
+ return true;
+}
+
/**
* snd_usb_endpoint_set_params: configure an snd_usb_endpoint
*
@@ -765,6 +810,7 @@ out_of_memory:
* @rate: the frame rate.
* @fmt: the USB audio format information
* @sync_ep: the sync endpoint to use, if any
+ * @subs: the substream that uses this endpoint as data endpoint
*
* Determine the number of URBs to be used on this endpoint.
* An endpoint must be configured before it can be started.
@@ -778,14 +824,23 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
unsigned int buffer_periods,
unsigned int rate,
struct audioformat *fmt,
- struct snd_usb_endpoint *sync_ep)
+ struct snd_usb_endpoint *sync_ep,
+ struct snd_usb_substream *subs)
{
int err;
if (ep->param_set || ep->use_count != 0) {
- snd_printk(KERN_WARNING "Unable to change format on ep #%x: already in use\n",
- ep->ep_num);
- return -EBUSY;
+ if (!subs ||
+ !snd_usb_endpoint_may_set_params(subs, pcm_format,
+ channels, period_bytes,
+ rate)) {
+ snd_printk(KERN_WARNING
+ "Unable to change format on ep #%x: already in use\n",
+ ep->ep_num);
+ return -EBUSY;
+ }
+ /* Endpoint already set with the same parameters */
+ return 0;
}
ep->param_set = true;
diff --git a/sound/usb/endpoint.h b/sound/usb/endpoint.h
index 1c7e8ee..188675d 100644
--- a/sound/usb/endpoint.h
+++ b/sound/usb/endpoint.h
@@ -16,7 +16,8 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
unsigned int buffer_periods,
unsigned int rate,
struct audioformat *fmt,
- struct snd_usb_endpoint *sync_ep);
+ struct snd_usb_endpoint *sync_ep,
+ struct snd_usb_substream *subs);
int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, bool can_sleep);
void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep);
@@ -32,4 +33,10 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
struct snd_usb_endpoint *sender,
const struct urb *urb);
+bool snd_usb_endpoint_may_set_params(struct snd_usb_substream *subs,
+ snd_pcm_format_t pcm_format,
+ unsigned int channels,
+ unsigned int period_bytes,
+ unsigned int rate);
+
#endif /* __USBAUDIO_ENDPOINT_H */
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index c165ccf..7895c81 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -635,6 +635,7 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
0, 0,
subs->cur_rate,
subs->cur_audiofmt,
+ NULL,
NULL);
/* Try to find the best matching audioformat. */
@@ -672,9 +673,18 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
0, 0,
subs->cur_rate,
sync_fp,
- NULL);
+ NULL,
+ sync_subs);
+ if (ret < 0)
+ return ret;
- return ret;
+ sync_subs->pcm_format = subs->pcm_format;
+ sync_subs->period_bytes = sync_period_bytes;
+ sync_subs->channels = sync_fp->channels;
+ sync_subs->cur_rate = subs->cur_rate;
+ sync_subs->data_endpoint = subs->sync_endpoint;
+
+ return 0;
}
/*
@@ -696,7 +706,8 @@ static int configure_endpoint(struct snd_usb_substream *subs)
subs->buffer_periods,
subs->cur_rate,
subs->cur_audiofmt,
- subs->sync_endpoint);
+ subs->sync_endpoint,
+ subs);
if (ret < 0)
return ret;
@@ -722,18 +733,38 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
struct snd_usb_substream *subs = substream->runtime->private_data;
struct audioformat *fmt;
int ret;
+ snd_pcm_format_t pcm_format;
+ unsigned int period_bytes;
+ unsigned int period_frames;
+ unsigned int buffer_periods;
+ unsigned int channels;
+ unsigned int rate;
ret = snd_pcm_lib_alloc_vmalloc_buffer(substream,
params_buffer_bytes(hw_params));
if (ret < 0)
return ret;
- subs->pcm_format = params_format(hw_params);
- subs->period_bytes = params_period_bytes(hw_params);
- subs->period_frames = params_period_size(hw_params);
- subs->buffer_periods = params_periods(hw_params);
- subs->channels = params_channels(hw_params);
- subs->cur_rate = params_rate(hw_params);
+ pcm_format = params_format(hw_params);
+ period_bytes = params_period_bytes(hw_params);
+ period_frames = params_period_size(hw_params);
+ buffer_periods = params_periods(hw_params);
+ channels = params_channels(hw_params);
+ rate = params_rate(hw_params);
+
+ if (!snd_usb_endpoint_may_set_params(subs, pcm_format, channels,
+ period_bytes, rate)) {
+ snd_printk(KERN_WARNING "Unable to set hw_params on substream (dir: %d), data EP in use\n",
+ subs->direction);
+ return -EBUSY;
+ }
+
+ subs->pcm_format = pcm_format;
+ subs->period_bytes = period_bytes;
+ subs->period_frames = period_frames;
+ subs->buffer_periods = buffer_periods;
+ subs->channels = channels;
+ subs->cur_rate = rate;
fmt = find_format(subs);
if (!fmt) {
@@ -767,9 +798,13 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
{
struct snd_usb_substream *subs = substream->runtime->private_data;
- subs->cur_audiofmt = NULL;
- subs->cur_rate = 0;
- subs->period_bytes = 0;
+ if (!subs->data_endpoint || subs->data_endpoint->use_count == 0) {
+ subs->cur_audiofmt = NULL;
+ subs->cur_rate = 0;
+ subs->period_bytes = 0;
+ subs->channels = 0;
+ }
+
down_read(&subs->stream->chip->shutdown_rwsem);
if (!subs->stream->chip->shutdown) {
stop_endpoints(subs, true);
--
1.8.1.5
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