pcm: direct: Fix for sync issue on xrun recover

If using very short periods, DSHARE/DSNOOP/DMIX may report underruns while in
status 'prepared'. This prohibits correct recovery. Now slave xrun conditions
for DSHARE/DSNOOP/DMIX are being handled properly.

Signed-off-by: Andreas Pape <apape@de.adit-jv.com>
Signed-off-by: Joshua Frkuska <joshua_frkuska@mentor.com>
Signed-off-by: Mounesh Sutar <mounesh_sutar@mentor.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

src/pcm/pcm_direct.c

@@ -550,6 +550,101 @@ int snd_pcm_direct_timer_stop(snd_pcm_direct_t *dmix)
 	return 0;
 }
 
+/*
+ * Recover slave on XRUN.
+ * Even if direct plugins disable xrun detection, there might be an xrun
+ * raised directly by some drivers.
+ * The first client recovers slave pcm.
+ * Each client needs to execute sw xrun handling afterwards
+ */
+int snd_pcm_direct_slave_recover(snd_pcm_direct_t *direct)
+{
+	int ret;
+	int semerr;
+
+	semerr = snd_pcm_direct_semaphore_down(direct,
+						   DIRECT_IPC_SEM_CLIENT);
+	if (semerr < 0) {
+		SNDERR("SEMDOWN FAILED with err %d", semerr);
+		return semerr;
+	}
+
+	if (snd_pcm_state(direct->spcm) != SND_PCM_STATE_XRUN) {
+		/* ignore... someone else already did recovery */
+		semerr = snd_pcm_direct_semaphore_up(direct,
+						     DIRECT_IPC_SEM_CLIENT);
+		if (semerr < 0) {
+			SNDERR("SEMUP FAILED with err %d", semerr);
+			return semerr;
+		}
+		return 0;
+	}
+
+	ret = snd_pcm_prepare(direct->spcm);
+	if (ret < 0) {
+		SNDERR("recover: unable to prepare slave");
+		semerr = snd_pcm_direct_semaphore_up(direct,
+						     DIRECT_IPC_SEM_CLIENT);
+		if (semerr < 0) {
+			SNDERR("SEMUP FAILED with err %d", semerr);
+			return semerr;
+		}
+		return ret;
+	}
+
+	if (direct->type == SND_PCM_TYPE_DSHARE) {
+		const snd_pcm_channel_area_t *dst_areas;
+		dst_areas = snd_pcm_mmap_areas(direct->spcm);
+		snd_pcm_areas_silence(dst_areas, 0, direct->spcm->channels,
+				      direct->spcm->buffer_size,
+				      direct->spcm->format);
+	}
+
+	ret = snd_pcm_start(direct->spcm);
+	if (ret < 0) {
+		SNDERR("recover: unable to start slave");
+		semerr = snd_pcm_direct_semaphore_up(direct,
+						     DIRECT_IPC_SEM_CLIENT);
+		if (semerr < 0) {
+			SNDERR("SEMUP FAILED with err %d", semerr);
+			return semerr;
+		}
+		return ret;
+	}
+	direct->shmptr->recoveries++;
+	semerr = snd_pcm_direct_semaphore_up(direct,
+						 DIRECT_IPC_SEM_CLIENT);
+	if (semerr < 0) {
+		SNDERR("SEMUP FAILED with err %d", semerr);
+		return semerr;
+	}
+	return 0;
+}
+
+/*
+ * enter xrun state, if slave xrun occurred
+ * @return: 0 - no xrun >0: xrun happened
+ */
+int snd_pcm_direct_client_chk_xrun(snd_pcm_direct_t *direct, snd_pcm_t *pcm)
+{
+	if (direct->shmptr->recoveries != direct->recoveries) {
+		/* no matter how many xruns we missed -
+		 * so don't increment but just update to actual counter
+		 */
+		direct->recoveries = direct->shmptr->recoveries;
+		pcm->fast_ops->drop(pcm);
+		/* trigger_tstamp update is missing in drop callbacks */
+		gettimestamp(&direct->trigger_tstamp, pcm->tstamp_type);
+		/* no timer clear:
+		 * if slave already entered xrun again the event is lost.
+		 * snd_pcm_direct_clear_timer_queue(direct);
+		 */
+		direct->state = SND_PCM_STATE_XRUN;
+		return 1;
+	}
+	return 0;
+}
+
 int snd_pcm_direct_poll_revents(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
 {
 	snd_pcm_direct_t *dmix = pcm->private_data;
@@ -572,6 +667,12 @@ int snd_pcm_direct_poll_revents(snd_pcm_t *pcm, struct pollfd *pfds, unsigned in
 	}
 	switch (snd_pcm_state(dmix->spcm)) {
 	case SND_PCM_STATE_XRUN:
+		/* recover slave and update client state to xrun
+		 * before returning POLLERR
+		 */
+		snd_pcm_direct_slave_recover(dmix);
+		snd_pcm_direct_client_chk_xrun(dmix, pcm);
+		/* fallthrough */
 	case SND_PCM_STATE_SUSPENDED:
 	case SND_PCM_STATE_SETUP:
 		events |= POLLERR;
@@ -1382,6 +1483,7 @@ int snd_pcm_direct_open_secondary_client(snd_pcm_t **spcmp, snd_pcm_direct_t *dm
 	dmix->slave_buffer_size = spcm->buffer_size;
 	dmix->slave_period_size = dmix->shmptr->s.period_size;
 	dmix->slave_boundary = spcm->boundary;
+	dmix->recoveries = dmix->shmptr->recoveries;
 
 	ret = snd_pcm_mmap(spcm);
 	if (ret < 0) {

src/pcm/pcm_direct.h

@@ -66,6 +66,7 @@ typedef struct {
 	char socket_name[256];			/* name of communication socket */
 	snd_pcm_type_t type;			/* PCM type (currently only hw) */
 	int use_server;
+	unsigned int recoveries;		/* no of executed recoveries on slave*/
 	struct {
 		unsigned int format;
 		snd_interval_t rate;
@@ -157,6 +158,7 @@ struct snd_pcm_direct {
 	int var_periodsize;		/* allow variable period size if max_periods is != -1*/
 	unsigned int channels;		/* client's channels */
 	unsigned int *bindings;
+	unsigned int recoveries;	/* mirror of executed recoveries on slave */
 	union {
 		struct {
 			int shmid_sum;			/* IPC global sum ring buffer memory identification */
@@ -324,7 +326,8 @@ int snd_pcm_direct_open_secondary_client(snd_pcm_t **spcmp, snd_pcm_direct_t *dm
 snd_pcm_chmap_query_t **snd_pcm_direct_query_chmaps(snd_pcm_t *pcm);
 snd_pcm_chmap_t *snd_pcm_direct_get_chmap(snd_pcm_t *pcm);
 int snd_pcm_direct_set_chmap(snd_pcm_t *pcm, const snd_pcm_chmap_t *map);
-
+int snd_pcm_direct_slave_recover(snd_pcm_direct_t *direct);
+int snd_pcm_direct_client_chk_xrun(snd_pcm_direct_t *direct, snd_pcm_t *pcm);
 int snd_timer_async(snd_timer_t *timer, int sig, pid_t pid);
 struct timespec snd_pcm_hw_fast_tstamp(snd_pcm_t *pcm);
 

src/pcm/pcm_dmix.c

@@ -434,15 +434,21 @@ static int snd_pcm_dmix_sync_ptr0(snd_pcm_t *pcm, snd_pcm_uframes_t slave_hw_ptr
 static int snd_pcm_dmix_sync_ptr(snd_pcm_t *pcm)
 {
 	snd_pcm_direct_t *dmix = pcm->private_data;
+	int err;
 
 	switch (snd_pcm_state(dmix->spcm)) {
 	case SND_PCM_STATE_DISCONNECTED:
 		dmix->state = SND_PCM_STATE_DISCONNECTED;
 		return -ENODEV;
+	case SND_PCM_STATE_XRUN:
+		if ((err = snd_pcm_direct_slave_recover(dmix)) < 0)
+			return err;
+		break;
 	default:
 		break;
 	}
-
+	if (snd_pcm_direct_client_chk_xrun(dmix, pcm))
+		return -EPIPE;
 	if (dmix->slowptr)
 		snd_pcm_hwsync(dmix->spcm);
 
@@ -828,12 +834,16 @@ static snd_pcm_sframes_t snd_pcm_dmix_mmap_commit(snd_pcm_t *pcm,
 
 	switch (snd_pcm_state(dmix->spcm)) {
 	case SND_PCM_STATE_XRUN:
-		return -EPIPE;
+		if ((err = snd_pcm_direct_slave_recover(dmix)) < 0)
+			return err;
+		break;
 	case SND_PCM_STATE_SUSPENDED:
 		return -ESTRPIPE;
 	default:
 		break;
 	}
+	if (snd_pcm_direct_client_chk_xrun(dmix, pcm))
+		return -EPIPE;
 	if (! size)
 		return 0;
 	snd_pcm_mmap_appl_forward(pcm, size);
@@ -841,8 +851,10 @@ static snd_pcm_sframes_t snd_pcm_dmix_mmap_commit(snd_pcm_t *pcm,
 		if ((err = snd_pcm_dmix_start_timer(pcm, dmix)) < 0)
 			return err;
 	} else if (dmix->state == SND_PCM_STATE_RUNNING ||
-		   dmix->state == SND_PCM_STATE_DRAINING)
-		snd_pcm_dmix_sync_ptr(pcm);
+		   dmix->state == SND_PCM_STATE_DRAINING) {
+		if ((err = snd_pcm_dmix_sync_ptr(pcm)) < 0)
+			return err;
+	}
 	if (dmix->state == SND_PCM_STATE_RUNNING ||
 	    dmix->state == SND_PCM_STATE_DRAINING) {
 		/* ok, we commit the changes after the validation of area */
@@ -858,10 +870,13 @@ static snd_pcm_sframes_t snd_pcm_dmix_mmap_commit(snd_pcm_t *pcm,
 static snd_pcm_sframes_t snd_pcm_dmix_avail_update(snd_pcm_t *pcm)
 {
 	snd_pcm_direct_t *dmix = pcm->private_data;
+	int err;
 	
 	if (dmix->state == SND_PCM_STATE_RUNNING ||
-	    dmix->state == SND_PCM_STATE_DRAINING)
-		snd_pcm_dmix_sync_ptr(pcm);
+	    dmix->state == SND_PCM_STATE_DRAINING) {
+		if ((err = snd_pcm_dmix_sync_ptr(pcm)) < 0)
+			return err;
+	}
 	return snd_pcm_mmap_playback_avail(pcm);
 }
 

src/pcm/pcm_dshare.c

@@ -162,7 +162,7 @@ static int snd_pcm_dshare_sync_ptr0(snd_pcm_t *pcm, snd_pcm_uframes_t slave_hw_p
 	snd_pcm_direct_t *dshare = pcm->private_data;
 	snd_pcm_uframes_t old_slave_hw_ptr, avail;
 	snd_pcm_sframes_t diff;
-	
+
 	old_slave_hw_ptr = dshare->slave_hw_ptr;
 	dshare->slave_hw_ptr = slave_hw_ptr;
 	diff = slave_hw_ptr - old_slave_hw_ptr;
@@ -202,15 +202,21 @@ static int snd_pcm_dshare_sync_ptr0(snd_pcm_t *pcm, snd_pcm_uframes_t slave_hw_p
 static int snd_pcm_dshare_sync_ptr(snd_pcm_t *pcm)
 {
 	snd_pcm_direct_t *dshare = pcm->private_data;
+	int err;
 
 	switch (snd_pcm_state(dshare->spcm)) {
 	case SND_PCM_STATE_DISCONNECTED:
 		dshare->state = SNDRV_PCM_STATE_DISCONNECTED;
 		return -ENODEV;
+	case SND_PCM_STATE_XRUN:
+		if ((err = snd_pcm_direct_slave_recover(dshare)) < 0)
+			return err;
+		break;
 	default:
 		break;
 	}
-
+	if (snd_pcm_direct_client_chk_xrun(dshare, pcm))
+		return -EPIPE;
 	if (dshare->slowptr)
 		snd_pcm_hwsync(dshare->spcm);
 
@@ -516,12 +522,16 @@ static snd_pcm_sframes_t snd_pcm_dshare_mmap_commit(snd_pcm_t *pcm,
 
 	switch (snd_pcm_state(dshare->spcm)) {
 	case SND_PCM_STATE_XRUN:
-		return -EPIPE;
+		if ((err = snd_pcm_direct_slave_recover(dshare)) < 0)
+			return err;
+		break;
 	case SND_PCM_STATE_SUSPENDED:
 		return -ESTRPIPE;
 	default:
 		break;
 	}
+	if (snd_pcm_direct_client_chk_xrun(dshare, pcm))
+		return -EPIPE;
 	if (! size)
 		return 0;
 	snd_pcm_mmap_appl_forward(pcm, size);
@@ -529,8 +539,10 @@ static snd_pcm_sframes_t snd_pcm_dshare_mmap_commit(snd_pcm_t *pcm,
 		if ((err = snd_pcm_dshare_start_timer(dshare)) < 0)
 			return err;
 	} else if (dshare->state == SND_PCM_STATE_RUNNING ||
-		   dshare->state == SND_PCM_STATE_DRAINING)
-		snd_pcm_dshare_sync_ptr(pcm);
+		   dshare->state == SND_PCM_STATE_DRAINING) {
+		if ((err = snd_pcm_dshare_sync_ptr(pcm)) < 0)
+			return err;
+	}
 	if (dshare->state == SND_PCM_STATE_RUNNING ||
 	    dshare->state == SND_PCM_STATE_DRAINING) {
 		/* ok, we commit the changes after the validation of area */
@@ -546,10 +558,13 @@ static snd_pcm_sframes_t snd_pcm_dshare_mmap_commit(snd_pcm_t *pcm,
 static snd_pcm_sframes_t snd_pcm_dshare_avail_update(snd_pcm_t *pcm)
 {
 	snd_pcm_direct_t *dshare = pcm->private_data;
+	int err;
 	
 	if (dshare->state == SND_PCM_STATE_RUNNING ||
-	    dshare->state == SND_PCM_STATE_DRAINING)
-		snd_pcm_dshare_sync_ptr(pcm);
+	    dshare->state == SND_PCM_STATE_DRAINING) {
+		if ((err = snd_pcm_dshare_sync_ptr(pcm)) < 0)
+			return err;
+	}
 	return snd_pcm_mmap_playback_avail(pcm);
 }
 

src/pcm/pcm_dsnoop.c

@@ -132,14 +132,21 @@ static int snd_pcm_dsnoop_sync_ptr(snd_pcm_t *pcm)
 	snd_pcm_direct_t *dsnoop = pcm->private_data;
 	snd_pcm_uframes_t slave_hw_ptr, old_slave_hw_ptr, avail;
 	snd_pcm_sframes_t diff;
-	
+	int err;
+
 	switch (snd_pcm_state(dsnoop->spcm)) {
 	case SND_PCM_STATE_DISCONNECTED:
 		dsnoop->state = SNDRV_PCM_STATE_DISCONNECTED;
 		return -ENODEV;
+	case SND_PCM_STATE_XRUN:
+		if ((err = snd_pcm_direct_slave_recover(dsnoop)) < 0)
+			return err;
+		break;
 	default:
 		break;
 	}
+	if (snd_pcm_direct_client_chk_xrun(dsnoop, pcm))
+		return -EPIPE;
 	if (dsnoop->slowptr)
 		snd_pcm_hwsync(dsnoop->spcm);
 	old_slave_hw_ptr = dsnoop->slave_hw_ptr;
@@ -410,12 +417,16 @@ static snd_pcm_sframes_t snd_pcm_dsnoop_mmap_commit(snd_pcm_t *pcm,
 
 	switch (snd_pcm_state(dsnoop->spcm)) {
 	case SND_PCM_STATE_XRUN:
-		return -EPIPE;
+		if ((err = snd_pcm_direct_slave_recover(dsnoop)) < 0)
+			return err;
+		break;
 	case SND_PCM_STATE_SUSPENDED:
 		return -ESTRPIPE;
 	default:
 		break;
 	}
+	if (snd_pcm_direct_client_chk_xrun(dsnoop, pcm))
+		return -EPIPE;
 	if (dsnoop->state == SND_PCM_STATE_RUNNING) {
 		err = snd_pcm_dsnoop_sync_ptr(pcm);
 		if (err < 0)