Re: [PATCH v3 3/3] ALSA: hda: add support for Huawei WMI micmute LED

[Takashi Iwai <tiwai@suse.de>]

On Thu, 22 Nov 2018 14:12:16 +0100,
Pavel Machek wrote:
> 
> On Tue 2018-11-20 13:19:26, Takashi Iwai wrote:
> > On Tue, 20 Nov 2018 12:51:59 +0100,
> > Pavel Machek wrote:
> > > 
> > > Hi!
> > > 
> > > > > You have general-purpose LED, yet you are treating it as "something
> > > > > special". That means ugly code (quoted above) and lack of flexibility.
> > > > > 
> > > > > For example, if my notebook lacks HDD LED, I can use scrollock LED for
> > > > > that instead. Or, in reverse way, maybe "mic mute" LED is not useful
> > > > > for me, and I'd like to use it for notifications instead.
> > > > 
> > > > I'm not against adding the LEDs device implementation for any exotic
> > > > usage.
> > > > 
> > > > But for the audio mute LED features, you'll need really lots of other
> > > > works if it were implemented via leds device.  That's the hardest
> > > > part, and a few lines of hooks solves it easily in the kernel side.
> > > > That's all about it.
> > > > 
> > > > If you are ready for submitting the real solutions in user-space side
> > > > (patching PulseAudio and whatever all existing sound daemons, and
> > > > creating yet another daemon for non-PA systems (another footprint,
> > > > lovely), and so on), we can happily delete such in-kernel hooks :)
> > > 
> > > I'm not saying we should move it to the userspace.
> > > 
> > > I'm saying this should be "normal" led. drivers/leds/led-huawei-acpi.c,
> > > or something. Perhaps this acpi stuff is so similar you don't really
> > > need .c code.
> > > 
> > > And then there should be a "mic muted" trigger. Similar to
> > > drivers/leds/trigger/ledtrig-disk.c.
> > 
> > And who will trigger this, e.g. when the mixer is muted?
> 
> Same code that does it now.

But it needs the binding, and currently it's done by querying the
exported symbol.  So we do need still that API.


Takashi