ALSA: firewire-tascam: share PCM buffer size for both direction

This commit allows ALSA firewire-tascam driver to share PCM buffer
size for both capture and playback PCM substream. When AMDTP domain
starts for one of the PCM substream, buffer size of the PCM substream
is stores to AMDTP domain structure. Some AMDTP streams have already
run with the buffer size when another PCM substream starts, therefore
the PCM substream has a constraint to its buffer size.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20191017155424.885-8-o-takashi@sakamocchi.jpSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/tascam/tascam-pcm.c

@@ -66,6 +66,7 @@ static int pcm_open(struct snd_pcm_substream *substream)
 	// at current one.
 	if (clock != SND_TSCM_CLOCK_INTERNAL || tscm->substreams_counter > 0) {
 		unsigned int frames_per_period = d->events_per_period;
+		unsigned int frames_per_buffer = d->events_per_buffer;
 		unsigned int rate;
 
 		err = snd_tscm_stream_get_rate(tscm, &rate);
@@ -83,6 +84,14 @@ static int pcm_open(struct snd_pcm_substream *substream)
 			mutex_unlock(&tscm->mutex);
 			goto err_locked;
 		}
+
+		err = snd_pcm_hw_constraint_minmax(substream->runtime,
+					SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
+					frames_per_buffer, frames_per_buffer);
+		if (err < 0) {
+			mutex_unlock(&tscm->mutex);
+			goto err_locked;
+		}
 	}
 
 	mutex_unlock(&tscm->mutex);
@@ -118,10 +127,11 @@ static int pcm_hw_params(struct snd_pcm_substream *substream,
 	if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN) {
 		unsigned int rate = params_rate(hw_params);
 		unsigned int frames_per_period = params_period_size(hw_params);
+		unsigned int frames_per_buffer = params_buffer_size(hw_params);
 
 		mutex_lock(&tscm->mutex);
 		err = snd_tscm_stream_reserve_duplex(tscm, rate,
-						     frames_per_period);
+					frames_per_period, frames_per_buffer);
 		if (err >= 0)
 			++tscm->substreams_counter;
 		mutex_unlock(&tscm->mutex);

sound/firewire/tascam/tascam-stream.c

@@ -384,7 +384,8 @@ void snd_tscm_stream_destroy_duplex(struct snd_tscm *tscm)
 }
 
 int snd_tscm_stream_reserve_duplex(struct snd_tscm *tscm, unsigned int rate,
-				   unsigned int frames_per_period)
+				   unsigned int frames_per_period,
+				   unsigned int frames_per_buffer)
 {
 	unsigned int curr_rate;
 	int err;
@@ -416,7 +417,7 @@ int snd_tscm_stream_reserve_duplex(struct snd_tscm *tscm, unsigned int rate,
 		}
 
 		err = amdtp_domain_set_events_per_period(&tscm->domain,
-							frames_per_period, 0);
+					frames_per_period, frames_per_buffer);
 		if (err < 0) {
 			fw_iso_resources_free(&tscm->tx_resources);
 			fw_iso_resources_free(&tscm->rx_resources);

sound/firewire/tascam/tascam.h

@@ -169,7 +169,8 @@ int snd_tscm_stream_init_duplex(struct snd_tscm *tscm);
 void snd_tscm_stream_update_duplex(struct snd_tscm *tscm);
 void snd_tscm_stream_destroy_duplex(struct snd_tscm *tscm);
 int snd_tscm_stream_reserve_duplex(struct snd_tscm *tscm, unsigned int rate,
-				   unsigned int frames_per_period);
+				   unsigned int frames_per_period,
+				   unsigned int frames_per_buffer);
 int snd_tscm_stream_start_duplex(struct snd_tscm *tscm, unsigned int rate);
 void snd_tscm_stream_stop_duplex(struct snd_tscm *tscm);