Re: ThinkPad T480s & LED_MUTE, LED_MICMUTE

[Henrique de Moraes Holschuh]

On Fri, 15 Jun 2018, Pali Rohár wrote:
> This means that kernel should not export any led class device. Or when
> exported, then "set" operation should always fail.

"not export" is right.

> > 2. Otherwise implement it in-kernel, so that userspace cannot unmute
> >    when the human has activated the "mute" switch, and the LED cannot be
> >    controlled by userspace to lie (report mute when it is not mute).
> 
> This looks like a good candidate to use led "trigger" interface. Create
> a mute trigger and attach it to that led device.

Maybe, as long as done in-kernel and not possible to mess with from
userspace.

> means set. What is SHDA doing, I have not figured out. It does not

Look at the HDA mixer state, SHDA is likely to be directly messing with
it.

-- 
  Henrique Holschuh