Re: [alsa-devel] [PATCH] dma: pl330: Add support for DMA_PAUSE command
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote:
On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org 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
At Thu, 15 May 2014 21:21:12 +0200, Lars-Peter Clausen wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote:
On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org 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.
Well, TRIGGER_SUSPEND is issued by PCM core no matter whether SNDRV_PCM_INFO_RESUME flag is set or not. The resume behavior depends on the flag (SNDRV_PCM_TRIGGER_RESUME is issued if the flag is set, otherwise the normal setup is done by alsa-lib at resume), but the suspend is always triggered in the same way.
So, PCM core assumes that the driver stops the stream somehow by SNDRV_PCM_TRIGGER_SUSPEND.
Takashi
On 05/16/2014 07:49 AM, Takashi Iwai wrote:
At Thu, 15 May 2014 21:21:12 +0200, Lars-Peter Clausen wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote:
On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org 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.
Well, TRIGGER_SUSPEND is issued by PCM core no matter whether SNDRV_PCM_INFO_RESUME flag is set or not. The resume behavior depends on the flag (SNDRV_PCM_TRIGGER_RESUME is issued if the flag is set, otherwise the normal setup is done by alsa-lib at resume), but the suspend is always triggered in the same way.
So, PCM core assumes that the driver stops the stream somehow by SNDRV_PCM_TRIGGER_SUSPEND.
Ok, so we should call terminate_all() when we get a SNDRV_PCM_TRIGGER_SUSPEND if the dmaengine driver does not support pauseing the transfer. Thanks for the clarification.
On a related note it seems like it is still possible to get PAUSE_PUSH/PAUSE_RELEASE events even if SNDRV_PCM_INFO_PAUSE is not set. Do you have an idea what should be the right thing to do in such a case? Return -ENOSYS?
- Lars
At Fri, 16 May 2014 12:51:51 +0200, Lars-Peter Clausen wrote:
On 05/16/2014 07:49 AM, Takashi Iwai wrote:
At Thu, 15 May 2014 21:21:12 +0200, Lars-Peter Clausen wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote: > > On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org > 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.
Well, TRIGGER_SUSPEND is issued by PCM core no matter whether SNDRV_PCM_INFO_RESUME flag is set or not. The resume behavior depends on the flag (SNDRV_PCM_TRIGGER_RESUME is issued if the flag is set, otherwise the normal setup is done by alsa-lib at resume), but the suspend is always triggered in the same way.
So, PCM core assumes that the driver stops the stream somehow by SNDRV_PCM_TRIGGER_SUSPEND.
Ok, so we should call terminate_all() when we get a SNDRV_PCM_TRIGGER_SUSPEND if the dmaengine driver does not support pauseing the transfer. Thanks for the clarification.
On a related note it seems like it is still possible to get PAUSE_PUSH/PAUSE_RELEASE events even if SNDRV_PCM_INFO_PAUSE is not set. Do you have an idea what should be the right thing to do in such a case? Return -ENOSYS?
That's weird. We have already a check in snd_pcm_pre_pause() in pcm_native.c to filter only for substreams with SNDRV_PCM_INFO_PAUSE flag.
Could you check in which code path it is triggered?
thanks,
Takashi
On 05/19/2014 10:37 AM, Takashi Iwai wrote:
At Fri, 16 May 2014 12:51:51 +0200, Lars-Peter Clausen wrote:
On 05/16/2014 07:49 AM, Takashi Iwai wrote:
At Thu, 15 May 2014 21:21:12 +0200, Lars-Peter Clausen wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote: > > On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote: >> >> On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org >> 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.
Well, TRIGGER_SUSPEND is issued by PCM core no matter whether SNDRV_PCM_INFO_RESUME flag is set or not. The resume behavior depends on the flag (SNDRV_PCM_TRIGGER_RESUME is issued if the flag is set, otherwise the normal setup is done by alsa-lib at resume), but the suspend is always triggered in the same way.
So, PCM core assumes that the driver stops the stream somehow by SNDRV_PCM_TRIGGER_SUSPEND.
Ok, so we should call terminate_all() when we get a SNDRV_PCM_TRIGGER_SUSPEND if the dmaengine driver does not support pauseing the transfer. Thanks for the clarification.
On a related note it seems like it is still possible to get PAUSE_PUSH/PAUSE_RELEASE events even if SNDRV_PCM_INFO_PAUSE is not set. Do you have an idea what should be the right thing to do in such a case? Return -ENOSYS?
That's weird. We have already a check in snd_pcm_pre_pause() in pcm_native.c to filter only for substreams with SNDRV_PCM_INFO_PAUSE flag.
Could you check in which code path it is triggered?
Uhm, yes, I was only looking at the code, but couldn't find the check that makes sure that the PAUSE_PUSH/PAUSE_RELEASE events are only triggered if SNDRV_PCM_INFO_PAUSE is set. Looks like I need a pair of glasses.
Thanks and sorry for the noise, - Lars
On 16 May 2014 00:51, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote:
On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org 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.
On 05/19/2014 05:10 AM, Tushar Behera wrote:
On 16 May 2014 00:51, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/15/2014 02:01 PM, Tushar Behera wrote:
On 14 May 2014 17:54, Lars-Peter Clausen lars@metafoo.de wrote:
On 05/14/2014 02:07 PM, Tushar Behera wrote:
On 14 May 2014 17:29, Jassi Brar jassisinghbrar@gmail.com wrote:
On Wed, May 14, 2014 at 8:53 AM, Tushar Behera tushar.behera@linaro.org 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
participants (3)
-
Lars-Peter Clausen -
Takashi Iwai -
Tushar Behera