Re: [PATCH] ALSA: hda: generic: Always add LED controls

[Jaroslav Kysela <perex@xxxxxxxx>]

On 05. 01. 24 0:41, Bernhard Seibold wrote:
> On Thu, Jan 04, 2024 at 10:46:04PM +0100, Jaroslav Kysela wrote:
> > On 04. 01. 24 20:14, Bernhard Seibold wrote:
> > > On Thu, Jan 04, 2024 at 05:41:48PM +0100, Takashi Iwai wrote:
> > > > On Thu, 04 Jan 2024 16:58:38 +0100,
> > > > Bernhard Seibold wrote:
> > > > > LEDs for mute and microphone mute can be added to any system via the
> > > > > audio-mute and audio-micmute triggers, e.g. via USB HID devices.
> > > > > Therefore, add the LED controls unconditionally.
> > > >
> > > > Hmm...  Won't your change lead to the sysfs entries always,
> > > > i.e. creating sysfs entries even if the device has no LED at all?
> > >
> > > This patch is not affecting create_mute_led_cdev, that function is still
> > > only called for some special systems via fixups, to create the actual
> > > LED classdevs that are present on there.
> > >
> > > What I'm trying to change is to have the led-ctls always available. They
> > > serve as input to the audio-mute and audio-micmute triggers, and these
> > > triggers should work on any system with HD Audio, not just a few.
> > >
> > > It would be even better to move the whole functionality into the sound
> > > core so that it works with other drivers as well, but since yesterday was
> > > the first time I even looked at sound code, I wouldn't even know where
> > > to start.
> >
> > You can attach controls using sysfs for special use cases. If the system has
> > audio LED driver controlled in other code, the HDA driver should be notified
> > somehow to create triggers, otherwise the default (current) functionality is
> > fine in my eyes.
>
> I've got a USB keyboard that has LEDs for mute and for microphone mute,
> and these currently do not work as expected. I'm not sure how special
> that use-case is, but I don't think expecting users to manually fiddle
> around in sysfs to get their keyboard LEDs working is a good solution.

I see your point (and tracked your name to hid-lenovo.c which creates 
mute/micmute LED drivers for Lenovo keyboards). The question is, if the audio 
triggers should be enabled blindly (all time) or when a LED driver exists and 
is active (runtime). In later case, this can be covered using new udev rules. 
Obviously, no manual configuration from users is expected.

						Jaroslav

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