[alsa-devel] [PATCH 2/2] alsa: dshare: allow missing bindings

[Adam Miartus]

From: Andreas Pape <apape at de.adit-jv.com>

The general idea of this patch is to be able to open the device without
defined bindings. This would start the audio clock without blocking
any channel.

This might be useful for hardware that requires running clock early at
system start and to be available even without application streaming
audio data.

Signed-off-by: Andreas Pape <apape at de.adit-jv.com>
Signed-off-by: Adam Miartus <amiartus at de.adit-jv.com>
---
 src/pcm/pcm_dshare.c      | 72 +++++++++++++++++++++++++++++++++++++++--------
 src/pcm/pcm_unsupported.h |  1 +
 2 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c
index b75809c..9008748 100644
--- a/src/pcm/pcm_dshare.c
+++ b/src/pcm/pcm_dshare.c
@@ -44,6 +44,7 @@
 #include <sys/un.h>
 #include <sys/mman.h>
 #include "pcm_direct.h"
+#include "pcm_unsupported.h"
 
 #ifndef PIC
 /* entry for static linking */
@@ -508,7 +509,8 @@ static int snd_pcm_dshare_close(snd_pcm_t *pcm)
 
 	if (dshare->timer)
 		snd_timer_close(dshare->timer);
-	do_silenca(pcm);
+	if (dshare->bindings)
+		do_silence(pcm);
 	snd_pcm_direct_semaphore_down(dshare, DIRECT_IPC_SEM_CLIENT);
 	dshare->shmptr->u.dshare.chn_mask &= ~dshare->u.dshare.chn_mask;
 	snd_pcm_close(dshare->spcm);
@@ -621,6 +623,54 @@ static void snd_pcm_dshare_dump(snd_pcm_t *pcm, snd_output_t *out)
 		snd_pcm_dump(dshare->spcm, out);
 }
 
+static const snd_pcm_ops_t snd_pcm_dshare_dummy_ops = {
+	.close = snd_pcm_dshare_close,
+	.info = snd_pcm_unsupported_info,
+	.hw_refine = snd_pcm_unsupported_hw_refine,
+	.hw_params = snd_pcm_unsupported_hw_params,
+	.hw_free = snd_pcm_unsupported_hw_free,
+	.sw_params = snd_pcm_unsupported_sw_params,
+	.channel_info = snd_pcm_unsupported_channel_info,
+	.dump = snd_pcm_unsupported_dump,
+	.nonblock = snd_pcm_unsupported_nonblock,
+	.async = snd_pcm_unsupported_async,
+	.mmap = snd_pcm_unsupported_mmap,
+	.munmap = snd_pcm_unsupported_munmap,
+	.get_chmap = snd_pcm_unsupported_get_chmap,
+	.set_chmap = snd_pcm_unsupported_set_chmap,
+};
+
+static const snd_pcm_fast_ops_t snd_pcm_dshare_fast_dummy_ops = {
+	.status = snd_pcm_unsupported_status,
+	.state = snd_pcm_unsupported_state,
+	.hwsync = snd_pcm_unsupported_hwsync,
+	.delay = snd_pcm_unsupported_delay,
+	.prepare = snd_pcm_unsupported_prepare,
+	.reset = snd_pcm_unsupported_reset,
+	.start = snd_pcm_unsupported_start,
+	.drop = snd_pcm_unsupported_drop,
+	.drain = snd_pcm_unsupported_drain,
+	.pause = snd_pcm_unsupported_pause,
+	.rewindable = snd_pcm_unsupported_rewindable,
+	.rewind = snd_pcm_unsupported_rewind,
+	.forwardable = snd_pcm_unsupported_forwardable,
+	.forward = snd_pcm_unsupported_forward,
+	.resume = snd_pcm_unsupported_resume,
+	.link = NULL,
+	.link_slaves = NULL,
+	.unlink = NULL,
+	.writei = snd_pcm_unsupported_writei,
+	.writen = snd_pcm_unsupported_writen,
+	.readi = snd_pcm_unsupported_readi,
+	.readn = snd_pcm_unsupported_readn,
+	.avail_update = snd_pcm_unsupported_avail_update,
+	.mmap_commit = snd_pcm_unsupported_mmap_commit,
+	.htimestamp = snd_pcm_unsupported_htimestamp,
+	.poll_descriptors = snd_pcm_unsupported_poll_descriptors,
+	.poll_descriptors_count = NULL,
+	.poll_revents = snd_pcm_unsupported_poll_revents,
+};
+
 static const snd_pcm_ops_t snd_pcm_dshare_ops = {
 	.close = snd_pcm_dshare_close,
 	.info = snd_pcm_direct_info,
@@ -713,12 +763,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 	if (ret < 0)
 		goto _err_nosem;
 		
-	if (!dshare->bindings) {
-		SNDERR("dshare: specify bindings!!!");
-		ret = -EINVAL;
-		goto _err_nosem;
-	}
-	
+
 	dshare->ipc_key = opts->ipc_key;
 	dshare->ipc_perm = opts->ipc_perm;
 	dshare->ipc_gid = opts->ipc_gid;
@@ -751,9 +796,14 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 		SNDERR("unable to create IPC shm instance");
 		goto _err;
 	}
-		
-	pcm->ops = &snd_pcm_dshare_ops;
-	pcm->fast_ops = &snd_pcm_dshare_fast_ops;
+
+	if (!dshare->bindings) {
+		pcm->ops = &snd_pcm_dshare_dummy_ops;
+		pcm->fast_ops = &snd_pcm_dshare_fast_dummy_ops;
+	} else {
+		pcm->ops = &snd_pcm_dshare_ops;
+		pcm->fast_ops = &snd_pcm_dshare_fast_ops;
+	}
 	pcm->private_data = dshare;
 	dshare->state = SND_PCM_STATE_OPEN;
 	dshare->slowptr = opts->slowptr;
@@ -843,7 +893,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
 		dshare->spcm = spcm;
 	}
 
-	for (chn = 0; chn < dshare->channels; chn++) {
+	for (chn = 0; dshare->bindings && (chn < dshare->channels); chn++) {
 		unsigned int dchn = dshare->bindings ? dshare->bindings[chn] : chn;
 		if (dchn != UINT_MAX)
 			dshare->u.dshare.chn_mask |= (1ULL << dchn);
diff --git a/src/pcm/pcm_unsupported.h b/src/pcm/pcm_unsupported.h
index 13e4d1b..5783222 100644
--- a/src/pcm/pcm_unsupported.h
+++ b/src/pcm/pcm_unsupported.h
@@ -114,6 +114,7 @@
 #define snd_pcm_unsupported_may_wait_for_avail_min \
 	snd1_pcm_unsupported_may_wait_for_avail_min
 
+void snd_pcm_unsupported_dump(snd_pcm_t *pcm, snd_output_t *out);
 int snd_pcm_unsupported_close(snd_pcm_t *pcm);
 int snd_pcm_unsupported_nonblock(snd_pcm_t *pcm, int nonblock);
 int snd_pcm_unsupported_async(snd_pcm_t *pcm, int sig, pid_t pid);
-- 
2.7.4