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>
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 @@
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 @@
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);