Re: [PATCH v10 00/11] HID: asus: Fix ASUS ROG Laptop's Keyboard backlight handling

[Hans de Goede]

Hi,

On 26-Nov-25 4:23 PM, Ilpo Järvinen wrote:
> On Wed, 26 Nov 2025, Antheas Kapenekakis wrote:

...

>> As for "HID: asus: early return for ROG devices" changing the name of
>> the devices of this driver, I will veto backporting it if it happens,
>> so inputplumber will have the two full months to remove the name
>> match. This is not a breaking change in the sense that software cannot
>> be made to work on both previous and latter versions and there is no
>> other software to my knowledge relying on name matches for Asus
>> keyboards.
> 
> Did Hans give some opinion about this rename earlier, at least I don't 
> remember nor could find from lore archives?

I don't remember commenting on this myself either.

So generally speaking there are plenty of cases where /dev/input/event#
nodes for a specific device have their name changed by some kernel patches.

Typically HID input devices are matched in userspace by their
bus:vend-id:prod-id triplet not by the name. The name might even
change by a fwupdate of the device itself.

So I'm not overly worried about this and inputplumber seems nice
enough and already is very much not a plug-and-play tool.

One possible concern with laptop keyboard input-device name changes
though is hwdb entries to fixup scancode -> ev-key-code mappings.

See: /lib/udev/hwdb.d/60-keyboard.hwdb on any standard Linux systems
an then the big comment at the top.

An input-device name change might break this match pattern:

#  - Input driver device name and DMI data match:
#      evdev:name:<input device name>:dmi:bvn*:bvr*:bd*:svn<vendor>:pn*
#    <input device name> is the name device specified by the
#    driver, <vendor> is the firmware-provided string exported
#    by the kernel DMI modalias, see /sys/class/dmi/id/modalias

As well as the extended version of this and for laptops with USB
keyboards this is the only match type which allows a DMI match
which is what we want for laptop kbd mappings. Looking at the Asus
section of the upstream 60-keyboard.hwdb I do not see any such
matches though.

There not being such matches kinda make sense since for USB-HID
devices any special scancode -> ev-key-code mappings are typically
handled in a vendor specific HID driver like hid-asus.

TL;DR: I think that the input-device name should be fine.

Regards,

Hans