Message-ID: <bd2ae598-3f13-f465-4bde-6ab364b79db3@redhat.com>
Date:   Sun, 19 Feb 2023 14:20:10 +0100
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Subject: Re: API for setting colors of RGB backlit keyboard zones (was [PATCH
 V3] platform/x86: hp-wmi: Support omen backlight control wmi-acpi methods)
To:     Pavel Machek <pavel@ucw.cz>,
        Rishit Bansal <rishitbansal0@gmail.com>
Cc:     Mark Gross <markgross@kernel.org>, linux-kernel@vger.kernel.org,
        platform-driver-x86@vger.kernel.org,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        Dan Murphy <dmurphy@ti.com>
References: <20230131235027.36304-1-rishitbansal0@gmail.com>
 <9b761996-d522-b0f8-6472-10e40e09e036@redhat.com>
 <65a11a89-e780-6d60-a40e-cd3245780762@gmail.com>
 <b83ad6ba-7d55-f309-5d7b-4a5ff77ff5a3@redhat.com>
 <02c96cfe-ab10-513f-fc36-f474dd227656@gmail.com>
 <544484b9-c0ac-2fd0-1f41-8fa94cb94d4b@redhat.com>
 <Y+I7xNqkq/X6Lag+@duo.ucw.cz>
 <3c48e204-780c-f78c-8219-267e297dc1e3@gmail.com>
 <ec5bc4a6-dc9f-90dd-0cf6-5fab47bb5fa6@redhat.com>
 <b11185d3-fbf3-a461-39bc-67bee4739e40@gmail.com>
 <Y/C7A9eCjpdbzYbz@duo.ucw.cz>
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From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <Y/C7A9eCjpdbzYbz@duo.ucw.cz>
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Hi,

On 2/18/23 12:48, Pavel Machek wrote:
> Hi!
> 
> 
>>> I do agree with you that we need to avoid kbd_backlight in the name to avoid causing existing upower code to have weird interactions with this (it supports / assumes there is only 1 kbd_backlight LED class device).
>>>
>>> So lets go with just these 4:
>>>
>>> /sys/class/leds/hp_omen::kbd_zoned_backlight-1/
>>> /sys/class/leds/hp_omen::kbd_zoned_backlight-2/
>>> /sys/class/leds/hp_omen::kbd_zoned_backlight-3/
>>> /sys/class/leds/hp_omen::kbd_zoned_backlight-4/
>>>
>>> Using the _zoned_ between kbd and baclight to avoid confusing the existing upower code. Then once this has landed we can look into extending upower support for this.
>>>
>>> Note the requested documentation patch should probably also explain that the _zoned_ was done deliberately to make current upower code ignore the devices.
>>>
> 
>>
>> This makes sense, I agree that the global LED file will cause more confusion
>> and hacks in the code. I'll start working on the  _zoned_ naming scheme with
>> 4 files + documentation changes and make a patch for this soon!
>>
> 
> /sys/class/leds/:rgb:kbd_zoned_backlight-4/ is better than what was
> suggested above.

Ah yes using rgb for the color part of the name makes sense.

> But we already use _1 suffix to deduplicate the, so
> I'm not sure this is best naming.


I guess we could try to actually name the zones, something like
(no idea if this are indeed the 4 zones):

:rgb:kbd_zoned_backlight-main
:rgb:kbd_zoned_backlight-wasd
:rgb:kbd_zoned_backlight-cursor
:rgb:kbd_zoned_backlight-numpad

Rishit any comments on this or improvements to it.

> There are keyboards with per-key backlight. How do you suggest to
> solve those?

I really think those fall into a separate category, currently AFAIK
all support for those use /dev/hidraw directly from userspace.

And any kernel API would need to likely be ioctl based, allowing
setting all the LEDs in a single syscall otherwise setting the
LEDs becomes to expensive / introduces to much latency when
doing software driven animations. So I think the best thing to
do there is to declare these out-of-scope for the classic
sysfs based LED class API.

Regards,

Hans