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

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Message-ID: <ba9085ce-ce3a-9c3a-f32c-df2995fd84a1@tuxedocomputers.com>
Date:   Tue, 30 May 2023 16:49:11 +0200
From:   Werner Sembach <wse@...edocomputers.com>
To:     Bastien Nocera <hadess@...ess.net>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] input: Add new keyboard backlight control keys to match
 modern notebooks

Am 30.05.23 um 16:28 schrieb 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@...edocomputers.com>
>> 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
I asked the KDE and Gnome maintainers for feedback: 
https://bugs.kde.org/show_bug.cgi?id=470453 
https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/issues/746
>
>>
>> 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