On 05/19/2014 05:10 AM, Tushar Behera wrote:
On 16 May 2014 00:51, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar <jassisinghbrar@xxxxxxxxx> wrote:
On Wed, May 14, 2014 at 8:53 AM, Tushar Behera
<tushar.behera@xxxxxxxxxx>
wrote:
While playing back audio, pmc_dmaengine requests the DMA channel to
stop DMA transmission through DMA_PAUSE command.
Currently PL330 driver doesn't support DMA pause command, leaving
the DMA state inconsistent when the system resumes. Instead, it would
be better to terminate the DMA transfer during suspend and restart
again during resume.
Tested with audio playback across a suspend-resume cycle.
What is pmc_dmaengine? How does DMA_PAUSE help, when there is no
DMA_RESUME?
Sorry, it is a typo.
sound/core/pcm_dmaengine.c:snd_dmaengine_pcm_trigger() -->
dmaengine_pause() is called during system suspend.
It is only called if the DMA driver has support for pausing and resuming
DMA
transfers. Or at least that is the intention.
- Lars
During suspend, snd_dmaengine_pcm_trigger():SNDRV_PCM_TRIGGER_SUSPEND
is called which unconditionally calls dmaengine_pause(). Should we
update snd_dmaengine_pcm_trigger() to check for DMA pause/resume
support and call dmaengine_pause() or dmaengine_terminate_all()
accordingly?
As far as I understand it we do not have to do anything for TRIGGER_SUSPEND
if we do not set the SNDRV_PCM_INFO_RESUME flag. It looks like
TRIGGER_SUSPEND is called unconditionally during suspend. But since the
error code is ignored it should be fine if we just call dmaengine_pause()
and that return -ENOSYS or similar.
Are you seeing an actual issue that you are trying to fix with your patch?
- Lars
Without this patch applied, if audio is playing back while suspend is
triggered, it doesn't playback after resume. Stopping the stream and
replaying works.
Ok, I think your second suggestion was correct. Call
dmaengine_terminate_all() instead of damengine_pause() in
snd_dmaengine_pcm_trigger() if the dmaengine driver does not support pausing
the transfer.
- Lars
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