Hi
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Friday, May 20, 2016 3:27 PM To: Shengjiu Wang Cc: perex@perex.cz; alsa-devel@alsa-project.org Subject: Re: [PATCH] pcm: Don't store the state for SND_PCM_STATE_SUSPENDED
On Wed, 18 May 2016 10:49:25 +0200, Takashi Iwai wrote:
On Wed, 18 May 2016 07:48:15 +0200, Shengjiu Wang wrote:
Hi Takashi
After adding your patch, I find another regression issue.
The alsa-lib may stop at
snd_pcm_write_areas() snd_pcm_wait_nocheck()
with suspend and resume test.
The reason is that:
In the beginning of playback, before the snd_pcm_dmix_start() is called, the system enter suspend. After resume,
snd_pcm_direct_resume()
update the dmix->state, and dmix->state is 3 (RUNNING, because the dmix->spcm is in RUNNING from snd_pcm_dmix_open()).
So in snd_pcm_write_areas() the state is RUNNING, then snd_pcm_start() will never be called, after a while, alsa-lib will stop at the snd_pcm_wait_nocheck() for the kernel will not wake up the timer.
A good point. Actually the culprit is that we declare dmix as if
it's
supporting the resume properly. Even if the resume works in the slave, dmix itself can't guarantee the proper resume. So, we should rather drop the whole resume stuff from dmix & co.
Below is the patch against to the current git tree. Give it a try.
thanks,
Takashi
From: Takashi Iwai tiwai@suse.de Subject: [PATCH] pcm: Remove resume support from dmix & co
PCM dmix and other plugins inherit the resume behavior from the slave PCM. However, the resume on dmix can't work reliably even if the slave PCM may do resume. The running state of each dmix stream is individual and may be PREPARED or RUN_PENDING while the slave PCM is already in RUNNING. And, when the slave PCM is resumed, the whole samples that have been already mapped are also played back, even if the corresponding dmix stream is still in SUSPENDED. Such inconsistencies can't be avoided as long as we manage each stream individually.
That said, dmix & co can't provide the proper resume support "by design". For aligning with it, we should drop the whole resume code and clear the PCM SND_PCM_INFO_RESUME flag.
Reported-by: Shengjiu Wang shengjiu.wang@nxp.com Signed-off-by: Takashi Iwai tiwai@suse.de
I performed a few tests and they seemed OK. I'm going to push the fix to git tree.
I tested your patch, after suspend and resume, the playback is stopped. It is caused by the DMA. DMA is not started after resume.
With your this change, DMA is not terminated but then is re-started. The Driver don't support this behavior.
Wang Shengjiu
thanks,
Takashi