ALSA: firewire-lib/dice/speakers: Add common PCM constraints for AMDTP streams

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.

[Fixed the compile error due to the missing "&" by tiwai]

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 1 insertions, 16 deletions

diff --git a/sound/firewire/dice.c b/sound/firewire/dice.c
index cd4c6b6d072e..a9a30c0161f1 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;