[alsa-devel] [PATCH] dmix: fix inconsistent status

[Takashi Iwai]

On Tue, 30 May 2017 17:33:08 +0200,
Takashi Iwai wrote:
> 
> On Fri, 26 May 2017 11:45:53 +0200,
> Cheng Sun wrote:
> > 
> > Hi all,
> > 
> > Following on from my previous email with subject "1.1.3 bug report:
> > dmix reports inconsistent status", this is a preliminary patch which
> > fixes the issue.
> > 
> > Comments are welcome. In particular note that I'm not very familiar
> > with this code, and in particular I still don't quite understand what
> > the original commit which introduced this bug (38a2d2e) is meant to be
> > doing.
> > 
> > Note also that if this patch is committable, based on the commit
> > comment for 38a2d2e I think there might be an analogous change to be
> > made to faf53c1.
> 
> Can it be simply like the patch below?

I came to believing this is the right way to go.  Below is the proper
patch.  If this works for you, I'm going to apply.


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai at suse.de>
Subject: [PATCH] pcm: dmix: Fix the inconsistent PCM state

The commit 38a2d2eda880 ("pcm: dmix: Do not discard slave reported
delay in...") changed the handling in snd_pcm_dmix_status() for taking
the actual delay from the slave PCM status.  Along with it, the commit
removed the line to update its own state altogether, as it had been
done originally in the dshare patch (commit faf53c197cab "pcm_dshare:
Do not discard slave reported delay..."), supposing that the slave PCM
keeps this same state.  However, for dmix/dshare, the PCM state may
differ from the slave, thus these changes resulted in the inconsistent
PCM state.

For dshare, the issue was already addressed by commit ad6957c61867
("plugin:dshare: wrong state reporting"), while the fix for dmix was
forgotten until now.

This patch restores the code to set the proper dmix PCM state again
like in the previous versions.

Fixes: 38a2d2eda880 ("pcm: dmix: Do not discard slave reported delay in...")
Reported-by: Cheng Sun <chengsun9 at gmail.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 src/pcm/pcm_dmix.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/pcm/pcm_dmix.c b/src/pcm/pcm_dmix.c
index c64ae5fc21f9..a6a8f3a84678 100644
--- a/src/pcm/pcm_dmix.c
+++ b/src/pcm/pcm_dmix.c
@@ -501,6 +501,7 @@ static int snd_pcm_dmix_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
 		break;
 	}
 
+	status->state = snd_pcm_dmix_state(pcm);
 	status->trigger_tstamp = dmix->trigger_tstamp;
 	status->avail = snd_pcm_mmap_playback_avail(pcm);
 	status->avail_max = status->avail > dmix->avail_max ? status->avail : dmix->avail_max;
-- 
2.13.0