[alsa-devel] Restore state around suspend/resume

[Takashi Iwai]

At Sun, 30 Nov 2008 10:38:27 -0800,
Dan Nicholson wrote:
> 
> On Sun, Nov 30, 2008 at 10:28 AM, Takashi Iwai <tiwai at suse.de> wrote:
> > At Sun, 30 Nov 2008 09:30:37 -0800,
> > Dan Nicholson wrote:
> >>
> >> On Sun, Nov 30, 2008 at 9:22 AM, Takashi Iwai <tiwai at suse.de> wrote:
> >> > At Sun, 30 Nov 2008 09:10:32 -0800,
> >> > Dan Nicholson wrote:
> >> >>
> >> >> On Sun, Nov 30, 2008 at 9:06 AM, Takashi Iwai <tiwai at suse.de> wrote:
> >> >> > At Sun, 30 Nov 2008 08:22:49 -0800,
> >> >> > Dan Nicholson wrote:
> >> >> >>
> >> >> >> On Sun, Nov 30, 2008 at 1:01 AM, Takashi Iwai <tiwai at suse.de> wrote:
> >> >> >> > I don't know who introduced it, but maybe it was a workaround...
> >> >> >>
> >> >> >> Yeah, I'm sure it was a workaround, but we're trying to get rid of the
> >> >> >> unnecessary ones now.
> >> >> >
> >> >> > Even for drivers without PM support, alsactl alone is useless.
> >> >> > So I suggest you to remove it.
> >> >>
> >> >> I'm sorry, but why useless? It seems that it would be useful to
> >> >> restore state from userspace if the driver isn't doing that on its
> >> >> own.
> >> >
> >> > Read alsactl "alone".  Without the combination of module unloading and
> >> > reloading, it's useless.
> >>
> >> So, are you saying that all drivers will maintain their state until
> >> they are unloaded?
> >
> > The drivers supporting PM do it, yes.
> 
> Then, for drivers that don't support PM, won't they lose their state
> across suspend? Shouldn't we save and restore it from userspace for
> those drivers?

They may lose the state.  They need anyway unloading and reloading the
driver at suspend/resume.  That's why I wrote alsactl "alone" doesn't
help.  It must be always coupled with unloading/reloading if it's
really needed.  Putting only alsactl is thus useless and misleading.


Takashi
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