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

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Message-ID: <44574d05-3a2a-2249-b808-7e929feea36d@tuxedocomputers.com>
Date:   Tue, 30 May 2023 16:28:51 +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

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

>
> 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