[alsa-devel] Restore state around suspend/resume
dbn.lists at gmail.com
Sun Nov 30 18:10:32 CET 2008
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:
>> > 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.
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
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