[Sound-open-firmware] Question about PM sleep

[Jaroslav Kysela]

Dne 13. 03. 20 v 16:53 Sridharan, Ranjani napsal(a):
> On Fri, Mar 13, 2020 at 8:43 AM Daniel Baluta <daniel.baluta at gmail.com>
> wrote:
> 
>> On Fri, Mar 13, 2020 at 5:34 PM Sridharan, Ranjani
>> <ranjani.sridharan at intel.com> wrote:
>>>
>>>
>>>
>>> On Fri, Mar 13, 2020 at 8:30 AM Daniel Baluta <daniel.baluta at gmail.com>
>> wrote:
>>>>
>>>> Hi Ranjani,
>>>>
>>>> While doing PM resume I get this warning message:
>>>>
>>>> root at imx8qxpmek:~# arecord -Dhw:0,0 -f S32_LE -r 48000 -c 2 z3.wav
>>>> Recording WAVE 'z3.wav' : Signed 32 bit Little Endian, Rate 48000 Hz,
>> Stereo
>>>> Suspended. Trying resume. Failed. Restarting stream. Done.
>>>>
>>>> Any idea what could cause it? It is because my stream doesn't really
>> support
>>>> resume?
>>>
>>> Hi Daniel,
>>>
>>> This is the expected behavior in SOF and it was suggested by Takashi.
>> Previously, we supported full resume in SOF, which meant that upon resuming
>> from suspend, you would get only the TRIGGER_RESUME. But we needed to also
>> get the prepare callback so that we could re-assign DMA stream tags upon
>> resuming. This is why aplay indicates that the stream didnt resume but
>> infact restarted from the previous position.
>>>
>>> Does this help?
>>
>> Indeed, it help. I will have a look at the discussion with Takashi.
>>
> Hi Daniel,
> 
> Here's the link to the discussion.
> https://mailman.alsa-project.org/pipermail/alsa-devel/2019-April/147440.html

In other words: ALSA PCM stream resume expects the full resume without the 
stream position change from the application POV. SOF driver cannot do it, thus 
it requires the full PCM stream restart.

						Jaroslav

-- 
Jaroslav Kysela <perex at perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.