[alsa-devel] Restore state around suspend/resume

[Dan Nicholson]

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?

> And, whether you need alsactl in pm script depends on the
> implementation.  On many distros, loading the sound driver will invoke
> "alsactl restore" automatically, thus you don't need it in the pm
> side.  But, for unloading the module, I guess "alsactl store" would be
> needed explicitly in the pm hook.

Yes, we don't want to unload the modules at suspend time unless
working around problems. And then, I'd suspect a udev or modprobe rule
would be more appropriate for restoring state.

--
Dan
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