[PATCH] fix card->power_lock congestion

[PATCH] fix card->power_lock congestion

[Clemens Ladisch]

snd_pcm_playback_drain() holds card->power_lock until the substream
has been drained completely. This prevents any other stream on that
card from preparing during this time (which is very annoying if one is
playing several small files which fit entirely into one buffer on a
multi-stream card like emu10k1 or ymfpci).

The patch below unlocks power_lock around the schedule() call. As a
consequence, it is possible to suspend a draining stream, but this has
already been possible before for streams in non-blocking mode.

Additionally, I think that snd_pcm_do_suspend() should call the
trigger callback when the stream is in the draining state, as the
playback needs to be stopped just as in the running state; and
similarly for snd_pcm_do_resume(). But I'm not really sure that I know
what I'm doing here. :)


Regards,
Clemens


-- 

- don't hold power lock while draining
- call trigger callback when suspending/resuming a draining substream


Index: alsa-kernel/core/pcm_native.c
===================================================================
RCS file: /cvsroot/alsa/alsa-kernel/core/pcm_native.c,v
retrieving revision 1.83
diff -u -r1.83 pcm_native.c
--- alsa-kernel/core/pcm_native.c	10 Oct 2003 14:44:56 -0000	1.83
+++ alsa-kernel/core/pcm_native.c	20 Oct 2003 06:56:15 -0000
@@ -888,7 +888,8 @@
 	snd_pcm_runtime_t *runtime = substream->runtime;
 	if (runtime->trigger_master != substream)
 		return 0;
-	if (runtime->status->suspended_state != SNDRV_PCM_STATE_RUNNING)
+	if (runtime->status->suspended_state != SNDRV_PCM_STATE_RUNNING &&
+	    runtime->status->suspended_state != SNDRV_PCM_STATE_DRAINING)
 		return 0;
 	return substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_SUSPEND);
 }
@@ -962,7 +963,8 @@
 	snd_pcm_runtime_t *runtime = substream->runtime;
 	if (runtime->trigger_master != substream)
 		return 0;
-	if (runtime->status->suspended_state != SNDRV_PCM_STATE_RUNNING)
+	if (runtime->status->suspended_state != SNDRV_PCM_STATE_RUNNING &&
+	    runtime->status->suspended_state != SNDRV_PCM_STATE_DRAINING)
 		return 0;
 	return substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_RESUME);
 }
@@ -1243,7 +1245,9 @@
 		}
 		set_current_state(TASK_INTERRUPTIBLE);
 		snd_pcm_stream_unlock_irq(substream);
+		snd_power_unlock(card);
 		tout = schedule_timeout(10 * HZ);
+		snd_power_lock(card);
 		snd_pcm_stream_lock_irq(substream);
 		if (tout == 0) {
 			state = runtime->status->state == SNDRV_PCM_STATE_SUSPENDED ? SUSPENDED : EXPIRED;




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Re: [PATCH] fix card->power_lock congestion

[Takashi Iwai]

At Mon, 20 Oct 2003 11:12:08 +0200 (METDST),
Clemens Ladisch wrote:
> 
> snd_pcm_playback_drain() holds card->power_lock until the substream
> has been drained completely. This prevents any other stream on that
> card from preparing during this time (which is very annoying if one is
> playing several small files which fit entirely into one buffer on a
> multi-stream card like emu10k1 or ymfpci).
> 
> The patch below unlocks power_lock around the schedule() call. As a
> consequence, it is possible to suspend a draining stream, but this has
> already been possible before for streams in non-blocking mode.
> 
> Additionally, I think that snd_pcm_do_suspend() should call the
> trigger callback when the stream is in the draining state, as the
> playback needs to be stopped just as in the running state; and
> similarly for snd_pcm_do_resume(). But I'm not really sure that I know
> what I'm doing here. :)

it should be ok, i think, since the playback and the drain states are
handled same for the lowlevel drivers.

i applied the patch to cvs.  please let me know if something wrong
happens...


thanks,

Takashi


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