[alsa-devel] [ALSA] ALSA Power Management, Drivers behaving unexpectedly after suspend/resume cycle

[Nobin Mathew]

I did some more investigation into this issue.

There are two cases, in the first case it is working after resume()
and in the second case it is not working after resume

1st Case:

1) boot the system
2)Load sound modules
2)mixer setting (alsactl restore 0)
3)Do power managemnt (sleep) suspend()
4)Come out of suspend, resume()
5)
sound is coming out in this case

2nd Case:
1)boot the system
2)load sound modules
3)mixer settings (alsactl restore 0)
4)Do playback aplay -M /usr/share/sounds/alsa/Side_Right.wav
5) Let aplay to completion and kill all alsa apps if any running.
6)Do power managemnt (sleep) suspend()
7)Come out of suspend, resume()
8)Do playback aplay -M /usr/share/sounds/alsa/Side_Right.wav

in this case no sound is coming out and i am getting underrun error.


I am attaching some logs, these are the ac97 codec register values at
various stages.

Mainly look at the register 3c.












On 5/25/07, Takashi Iwai <tiwai at suse.de> wrote:
> At Fri, 25 May 2007 13:39:40 +0100,
> Liam Girdwood wrote:
> >
> > On Fri, 2007-05-25 at 17:34 +0530, Nobin Mathew wrote:
> > > Every ALSA driver is calling these for suspend
> > >
> > > snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
> > > snd_pcm_suspend_all(pcm[i]);
> > >
> > > And for resume
> > > snd_power_change_state(card, SNDRV_CTL_POWER_D0)
> > >
> > >
> > > In ALSA ASoC no driver is calling any of this, even not in soc-core.c
> > >
> > > My driver is an ASoC driver and I am also not calling these functions
> > >
> > > Will this cause any Issue?
> > >
> >
> > These should probably be called to inform the upper layers of the PM
> > state. Can you log a bug for this in ALSA bugzilla.
> >
> > Fwiw, this _shouldn't_ effect your resume. You should still see calls to
> > trigger for your DMA / AC97 to re-start transmission of PCM data.
>
> I think this does matter.  Without calling snd_pcm_suspend*(), the
> stream is assumed to be still active, thus eventually neither prepare
> nor trigger is called at resume.  If the hardware is perfectly
> resumed as it was before suspend, it may still work somehow.
>
> However, usually it's impossible to resume the hardware perfectly.
> Thus, we need one stop the stream via snd_pcm_suspend*(), and let apps
> (or OSS layer) parepare (if needed) and restart the stream again.
>
>
> Takashi
>
-------------- next part --------------
0:00 = 6174
0:02 = 8080
0:04 = 4040
0:06 = 8080
0:08 = c880
0:0a = 6808
0:0c = 6808
0:0e = 0808
0:10 = 00fa
0:12 = 0080
0:14 = d607
0:16 = aaa0
0:18 = aaa0
0:1a = aaa0
0:1c = 00a0
0:1e = 000f
0:20 = 0f0f
0:22 = 0040
0:24 = 0000
0:26 = 000f
0:28 = 0405
0:2a = 0411
0:2c = bb80
0:2e = bb80
0:30 = 0000
0:32 = bb80
0:34 = 0000
0:36 = 4523
0:38 = 0000
0:3a = 2000
0:3c = 1bff
0:3e = fddf
0:40 = 0000
0:42 = 0000
0:44 = 0080
0:46 = 8607
0:48 = 0000
0:4a = 0000
0:4c = fffe
0:4e = ffff
0:50 = 0000
0:52 = 0000
0:54 = 09a0
0:56 = fffe
0:58 = 4000
0:5a = 0000
0:5c = 0000
0:5e = 0000
0:60 = b032
0:62 = 3e00
0:64 = 0000
0:66 = 0000
0:68 = 0060
0:6a = 0000
0:6c = 0000
0:6e = 0000
0:70 = 0000
0:72 = 0000
0:74 = 0000
0:76 = 0006
0:78 = 0001
0:7a = 0000
0:7c = 574d
0:7e = 4c13
-------------- next part --------------
0:00 = 6174
0:02 = 8080
0:04 = 4040
0:06 = 8080
0:08 = c880
0:0a = 6808
0:0c = 6808
0:0e = 0808
0:10 = 00fa
0:12 = 0080
0:14 = d607
0:16 = aaa0
0:18 = aaa0
0:1a = aaa0
0:1c = 00a0
0:1e = 000f
0:20 = 0f0f
0:22 = 0040
0:24 = 0000
0:26 = 000f
0:28 = 0405
0:2a = 0411
0:2c = bb80
0:2e = bb80
0:30 = 0000
0:32 = bb80
0:34 = 0000
0:36 = 4523
0:38 = 0000
0:3a = 2000
0:3c = 3bff
0:3e = fddf
0:40 = 0000
0:42 = 0000
0:44 = 0080
0:46 = 8607
0:48 = 0000
0:4a = 0000
0:4c = fffe
0:4e = ffff
0:50 = 0000
0:52 = 0000
0:54 = 09a0
0:56 = fffe
0:58 = 4000
0:5a = 0000
0:5c = 0000
0:5e = 0000
0:60 = b032
0:62 = 3e00
0:64 = 0000
0:66 = 0000
0:68 = 0060
0:6a = 0000
0:6c = 0000
0:6e = 0000
0:70 = 0000
0:72 = 0000
0:74 = 0000
0:76 = 0006
0:78 = 0001
0:7a = 0000
0:7c = 574d
0:7e = 4c13
-------------- next part --------------
0:00 = 6174
0:02 = 8080
0:04 = 4040
0:06 = 8080
0:08 = c880
0:0a = 6808
0:0c = 6808
0:0e = 0808
0:10 = 00fa
0:12 = 0080
0:14 = d607
0:16 = aaa0
0:18 = aaa0
0:1a = aaa0
0:1c = 00a0
0:1e = 000f
0:20 = 0f0f
0:22 = 0040
0:24 = 0000
0:26 = 000f
0:28 = 0405
0:2a = 0410
0:2c = bb80
0:2e = bb80
0:30 = 0000
0:32 = bb80
0:34 = 0000
0:36 = 4523
0:38 = 0000
0:3a = 2000
0:3c = 3afb
0:3e = fddf
0:40 = 0000
0:42 = 0000
0:44 = 0080
0:46 = 0000
0:48 = 0000
0:4a = 0000
0:4c = fffe
0:4e = ffff
0:50 = 0000
0:52 = 0000
0:54 = 09a0
0:56 = fffe
0:58 = 4000
0:5a = 0000
0:5c = 0000
0:5e = 0000
0:60 = b032
0:62 = 3e00
0:64 = 0000
0:66 = 0000
0:68 = 0060
0:6a = 0000
0:6c = 0000
0:6e = 0000
0:70 = 0000
0:72 = 0000
0:74 = 0000
0:76 = 0006
0:78 = 0001
0:7a = 0000
0:7c = 574d
0:7e = 4c13
-------------- next part --------------
0:00 = 6174
0:02 = 8080
0:04 = 4040
0:06 = 8080
0:08 = c880
0:0a = 6808
0:0c = 6808
0:0e = 0808
0:10 = 00fa
0:12 = 0080
0:14 = d607
0:16 = aaa0
0:18 = aaa0
0:1a = aaa0
0:1c = 00a0
0:1e = 000f
0:20 = 0f0f
0:22 = 0040
0:24 = 0000
0:26 = 000f
0:28 = 0405
0:2a = 0411
0:2c = bb80
0:2e = bb80
0:30 = 0000
0:32 = bb80
0:34 = 0000
0:36 = 4523
0:38 = 0000
0:3a = 2000
0:3c = 1afb
0:3e = fddf
0:40 = 0000
0:42 = 0000
0:44 = 0080
0:46 = 8607
0:48 = 0000
0:4a = 0000
0:4c = fffe
0:4e = ffff
0:50 = 0000
0:52 = 0000
0:54 = 09a0
0:56 = fffe
0:58 = 4000
0:5a = 0000
0:5c = 0000
0:5e = 0000
0:60 = b032
0:62 = 3e00
0:64 = 0000
0:66 = 0000
0:68 = 0060
0:6a = 0000
0:6c = 0000
0:6e = 0000
0:70 = 0000
0:72 = 0000
0:74 = 0000
0:76 = 0006
0:78 = 0001
0:7a = 0000
0:7c = 574d
0:7e = 4c13