[alsa-devel] Restore state around suspend/resume
tiwai at suse.de
Sun Nov 30 18:06:30 CET 2008
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:
> > At Sat, 29 Nov 2008 12:40:02 -0800,
> > Dan Nicholson wrote:
> >> Hi,
> >> Currently, suspending the computer via pm-suspend (as done from HAL),
> >> causes the ALSA state to be stored and restored via alsactl. Here's
> >> what the hook looks like:
> >> http://cgit.freedesktop.org/pm-utils/tree/pm/sleep.d/65alsa
> >> Is this still necessary on recent kernels? Is there a list of drivers
> >> which properly maintain state across suspend/resume? We're trying to
> >> cut down on the amount of work done in userspace which slows down
> >> suspend cycles.
> > The all drivers with PM support should have do store/restore the
> > mixer states. For such drivers, calling alsactl is just a waste of
> > time.
> Thanks. Which drivers don't have PM support?
Many. Look though the kernel tree codes under sound directory
that has no suspend and resume callbacks.
> > 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.
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