This commit adds common PCM constraints according to current firewire-lib implementation.
1.Maximum width for each sample is limited by 24. AM824 in IEC 61883-6 can deliver 24bit data.
2. Minimum time for period is 5msec. Apply the old value. For shorter latency, further works are needed.
3. In blocking mode, frames per period/buffer is aligned to 32. Each packet can include some frames depending on its sampling rate. In blocking mode, the number equals to SYT_INTERVAL. Currently firewire-lib can schedule snd_pcm_period_elapsed() for each packet. So, for accurate PCM interrupt, the number of frames per period/buffer should be aligned to SYT_INTERVAL. Currently firewire-lib is lack of better rules to achieve this. So LCM of each value of SYT_INTERVALs (=32) is applied. This can be improved for further work.
Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp --- sound/firewire/amdtp.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++ sound/firewire/amdtp.h | 3 +++ sound/firewire/dice.c | 17 +------------- sound/firewire/speakers.c | 8 +------ 4 files changed, 61 insertions(+), 23 deletions(-)
diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c index 3475b76..ac8c358 100644 --- a/sound/firewire/amdtp.c +++ b/sound/firewire/amdtp.c @@ -13,6 +13,7 @@ #include <linux/slab.h> #include <linux/sched.h> #include <sound/pcm.h> +#include <sound/pcm_params.h> #include <sound/rawmidi.h> #include "amdtp.h"
@@ -105,6 +106,61 @@ const unsigned int amdtp_syt_intervals[CIP_SFC_COUNT] = { EXPORT_SYMBOL(amdtp_syt_intervals);
/** + * amdtp_stream_add_pcm_hw_constraints - add hw constraints for PCM substream + * @s: the AMDTP stream, which must be initialized. + * @runtime: the PCM substream runtime + */ +int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s, + struct snd_pcm_runtime *runtime) +{ + int err; + + /* AM824 in IEC 61883-6 can deliver 24bit data */ + err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24); + if (err < 0) + goto end; + + /* + * Currently firewire-lib processes 16 packets in one software + * interrupt callback. This equals to 2msec but actually the + * interval of the interrupts has a jitter. + * Additionally, even if adding a constraint to fit period size to + * 2msec, actual calculated frames per period doesn't equal to 2msec, + * depending on sampling rate. + * Anyway, the interval to call snd_pcm_period_elapsed() cannot 2msec. + * Here let us use 5msec for safe period interrupt. + */ + err = snd_pcm_hw_constraint_minmax(runtime, + SNDRV_PCM_HW_PARAM_PERIOD_TIME, + 5000, UINT_MAX); + if (err < 0) + goto end; + + /* Non-Blocking stream has no more constraints */ + if (!(s->flags & CIP_BLOCKING)) + goto end; + + /* + * One AMDTP packet can include some frames. In blocking mode, the + * number equals to SYT_INTERVAL. So the number is 8, 16 or 32, + * depending on its sampling rate. For accurate period interrupt, it's + * preferrable to aligh period/buffer sizes to current SYT_INTERVAL. + * + * TODO: These constraints can be improved with propper rules. + * Currently apply LCM of SYT_INTEVALs. + */ + err = snd_pcm_hw_constraint_step(runtime, 0, + SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 32); + if (err < 0) + goto end; + err = snd_pcm_hw_constraint_step(runtime, 0, + SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 32); +end: + return err; +} +EXPORT_SYMBOL(amdtp_stream_add_pcm_hw_constraints); + +/** * amdtp_stream_set_parameters - set stream parameters * @s: the AMDTP stream to configure * @rate: the sample rate diff --git a/sound/firewire/amdtp.h b/sound/firewire/amdtp.h index db60425..d6bb7eb 100644 --- a/sound/firewire/amdtp.h +++ b/sound/firewire/amdtp.h @@ -64,6 +64,7 @@ enum cip_sfc { struct fw_unit; struct fw_iso_context; struct snd_pcm_substream; +struct snd_pcm_runtime; struct snd_rawmidi_substream;
enum amdtp_stream_direction { @@ -130,6 +131,8 @@ int amdtp_stream_start(struct amdtp_stream *s, int channel, int speed); void amdtp_stream_update(struct amdtp_stream *s); void amdtp_stream_stop(struct amdtp_stream *s);
+int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s, + struct snd_pcm_runtime *runtime); void amdtp_stream_set_pcm_format(struct amdtp_stream *s, snd_pcm_format_t format); void amdtp_stream_pcm_prepare(struct amdtp_stream *s); diff --git a/sound/firewire/dice.c b/sound/firewire/dice.c index cd4c6b6..a9a30c0 100644 --- a/sound/firewire/dice.c +++ b/sound/firewire/dice.c @@ -420,22 +420,7 @@ static int dice_open(struct snd_pcm_substream *substream) if (err < 0) goto err_lock;
- err = snd_pcm_hw_constraint_step(runtime, 0, - SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 32); - if (err < 0) - goto err_lock; - err = snd_pcm_hw_constraint_step(runtime, 0, - SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 32); - if (err < 0) - goto err_lock; - - err = snd_pcm_hw_constraint_minmax(runtime, - SNDRV_PCM_HW_PARAM_PERIOD_TIME, - 5000, UINT_MAX); - if (err < 0) - goto err_lock; - - err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24); + err = amdtp_stream_add_pcm_hw_constraints(&dice->stream, runtime); if (err < 0) goto err_lock;
diff --git a/sound/firewire/speakers.c b/sound/firewire/speakers.c index c07e7cd..3427527 100644 --- a/sound/firewire/speakers.c +++ b/sound/firewire/speakers.c @@ -167,13 +167,7 @@ static int fwspk_open(struct snd_pcm_substream *substream) if (err < 0) return err;
- err = snd_pcm_hw_constraint_minmax(runtime, - SNDRV_PCM_HW_PARAM_PERIOD_TIME, - 5000, UINT_MAX); - if (err < 0) - return err; - - err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24); + err = amdtp_stream_add_pcm_hw_constraints(fwspk->stream, runtime); if (err < 0) return err;