Re: [PATCH] input: Add new keyboard backlight control keys to match modern notebooks

[Werner Sembach]

Hi,

Am 30.05.23 um 15:33 schrieb Bastien Nocera:
> On Tue, 2023-05-30 at 13:05 +0200, Werner Sembach wrote:
> > The old three KEY_KBDILLUM* keycodes don't reflect the current
> > situation
> > modern notebooks anymore. Especially the ones with RGB keyboards.
> >
> > e.g.
> > - Clevo NL50NU has a toggle, an up, a down and a color-cycle key
> > - TongFang PH4ARX1 doesn't have a toggle key, but one that cycles
> > through
> >    off, half-brightness, and full-brightness.
> >
> > Also, on some devices these keys are already implemented in firmware.
> > It
> > would still be nice if there is a way to let userspace know when one
> > of
> > these keys is pressed to display the OSD, but don't advice it to
> > actually
> > do anything. This is the intended purpose of the KEY_KBDILLUMCHANGE
> > define.
> >
> > Signed-off-by: Werner Sembach <wse@xxxxxxxxxxxxxxxxxxx>
> Can you please point to the user-space patches (or issues filed) that
> would integrate the support for those keycodes, and make the key
> presses do something?

I'm sorry to say that these don't exist yet. So I guess the process is similar 
to DRM uAPI additions? 
https://docs.kernel.org/gpu/drm-uapi.html#open-source-userspace-requirements

> Has anyone tested that those keycodes are fit for purpose when mixed
> with other brightness changes that don't happen through key presses?

Color control is not yet implemented in any DE afaik, so there is not yet a 
collision with the color cycle key.

For the brightness cycle key, I would assume that it functions the same as the 
brightness up key unless brightness == brightness max. In this case it sets 
brightness to 0. I don't see a logical collision here as brightness up and 
brightness down are already implemented just fine in most DEs

> > ---
> >   include/uapi/linux/input-event-codes.h | 4 ++++
> >   1 file changed, 4 insertions(+)
> >
> > diff --git a/include/uapi/linux/input-event-codes.h
> > b/include/uapi/linux/input-event-codes.h
> > index 022a520e31fc2..05287bf9a77f7 100644
> > --- a/include/uapi/linux/input-event-codes.h
> > +++ b/include/uapi/linux/input-event-codes.h
> > @@ -803,6 +803,10 @@
> >   #define BTN_TRIGGER_HAPPY39            0x2e6
> >   #define BTN_TRIGGER_HAPPY40            0x2e7
> >   
> > +#define KEY_KBDILLUMCYCLE              0x2e8
> > +#define KEY_KBDILLUMCOLORCYCLE         0x2e9
> > +#define KEY_KBDILLUMCHANGE             0x2ea
> > +
> >   /* We avoid low common keys in module aliases so they don't get
> > huge. */
> >   #define KEY_MIN_INTERESTING    KEY_MUTE
> >   #define KEY_MAX                        0x2ff