linux-kernel - Re: [PATCH RESEND v2 1/4] HID: hid-appletb-bl: add driver for the backlight of Apple Touch Bars

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Message-ID: <034oq462-2on2-9rns-q99n-1p0rn5s66n65@xreary.bet>
Date: Tue, 4 Feb 2025 03:17:22 +0100 (CET)
From: Jiri Kosina <jikos@...nel.org>
To: Aditya Garg <gargaditya08@...e.com>
cc: "bentiss@...nel.org" <bentiss@...nel.org>, 
    Benjamin Tissoires <benjamin.tissoires@...hat.com>, 
    Thomas Weißschuh <linux@...ssschuh.net>, 
    Thomas Weißschuh <thomas@...ch.de>, 
    Kerem Karabay <kekrby@...il.com>, 
    Orlando Chamberlain <orlandoch.dev@...il.com>, 
    Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, 
    "linux-input@...r.kernel.org" <linux-input@...r.kernel.org>
Subject: Re: [PATCH RESEND v2 1/4] HID: hid-appletb-bl: add driver for the
 backlight of Apple Touch Bars

On Tue, 4 Feb 2025, Aditya Garg wrote:

> You might have noticed that the hid-apple driver has code for the magic 
> backlight. Now we have a case of MacBook Air 2020, which does not have a 
> touchbar but still shows presence of the touchbar backlight device, just 
> because it needs it for the keyboard backlight. In case we merge both 
> the backlight and touchbar code in a driver, on that model, the 
> backlight breaks. If kept separate, the touchbar driver simply doesn't 
> load and backlight works.

Sorry for being dense, but does that mean that it's either hid-appletb-bl 
or hid-apple, but never both to make a good user experience on those 
devices?

If so, can you please point out what exactly is the reason?

Either those have different VID/PID combination, and then it can be easily 
made conditional both in code and in runtime.
Are we talking about conflicting VID/PID combinations, some of them 
needing current hid-apple, and some of them needing (in a mutually 
exclusive way) hid-appletb-bl?

Thanks,

-- 
Jiri Kosina
SUSE Labs