Re: [PATCH 0/5] ALSA: control - add generic LED trigger code

[Jaroslav Kysela <perex@perex.cz>]

Dne 11. 02. 21 v 18:15 Takashi Iwai napsal(a):

>> Jaroslav Kysela (5):
>>   ALSA: control - introduce snd_ctl_notify_one() helper
>>   ALSA: control - add layer registration routines
>>   ALSA: control - add generic LED trigger module as the new control
>>     layer
>>   ALSA: HDA - remove the custom implementation for the audio LED trigger
>>   ALSA: control - add sysfs support to the LED trigger module

> One thing I still miss from the picture is how to deal with the case
> like AMD ACP.  It has no mixer control to bundle with the LED trigger.
> Your idea is to make a (dummy) user element and tie the LED trigger
> with it?

Yes, the user-space code which guarantee the silence stream should create an
user space control with the appropriate LED group access bits. The alsa-lib's
softvol PCM plugin can do this silencing for example.

> Another slight concern is the possible regression: by moving the
> mute-LED mode enum stuff into the sysfs, user will get
> incompatibilities after the kernel update.  And it's not that trivial
> to change the sysfs entry as default for each user.
> It needs some detailed documentation or some temporary workaround
> (e.g. keep providing the controls for now but warns if the value is
> changed from the default value via the controls).

I don't think that we have a user space application which is using those
controls (Pulseaudio or so..) in an abstract way. I think that it's really
minor issue. We should probably concentrate for the main designed purpose
(notify about the mute / silent state) and handle those add-on features as an
experimental stuff.

					Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.