Re: [PATCH v5 0/2] HID: generic: add LampArray support via hid-lamparray helper

[Armin Wolf <W_Armin@gmx.de>]

Am 03.09.26 um 09:35 schrieb Aaron Erhardt:

> Add a new hid-lamparray helper module and integrate it with the
> hid-generic driver.
>
> While more complex lamparray handling should be done in userspace via
> hidraw, providing a small module to add basic lamparray support makes it
> possible for userspace software to interact with lamparrays by simply
> using well-known APIs of the LED subsystem. One use-case would be to
> enable desktop environments to support keyboard backlight control out of
> the box for HID lamparray devices without having to implement the whole
> HID protocol themselves.
>
> This patch is based on previous discussions:
> https://lore.kernel.org/all/1fb08a74-62c7-4d0c-ba5d-648e23082dcb@tuxedocomputers.com/
>
> The helper provides basic support for devices exposing a
> Lighting/LampArray application collection (usage page 0x59) and
> registers a single-zone RGB LED representation via the LED
> subsystem.
>
> hid-generic now checks for LampArray support after hid_parse() and
> optionally registers a lamparray instance. Failures in the helper
> do not abort device probe to keep the driver logic otherwise unchanged.
>
> LampArray resources are released on driver remove.
>
> This commit was successfully tested on the Microsoft MacroPad reference
> implementation (https://github.com/microsoft/RP2040MacropadHidSample
> 1d6c3ad) and in combination with the tuxedo_nb04_wmi driver, albeit
> only fully functional with a recent fix posted to the LKML
> (https://lore.kernel.org/all/20260826081149.235487-2-aer@tuxedocomputers.com).

Nice work, it works on my ASUS Prime B650-Plus. However the behavior of the brightness
attribute is a bit strange:

- manually setting "brightness" does not change anything (max. is 1)
- setting RGB to "0 0 0" causes "brightness" to become 0
- setting RGB to a non-zero value causes "brightness" to become 1

Any idea why this happens? I can check if the same problems also exists under Windows,
if requested.

Thanks,
Armin Wolf

> v5:
> - Proper hardware detection (no quirks necessary anymore)
> - Add documentation for new sysfs knob
> - Pass limits of the device to sysfs (intesities & brightness)
> - More flexible Kconfig (use tristate)
> - Improved locking
> - Several memory leak and (de-)initialization fixes
> - Don't read current color values from hardware (the HID spec does not
>    offer this option)
> - Remove redundant report dump functionality
> v4:
> - Restrict CONFIG_HID_LAMPARRAY to built-in configurations only to fix
>    additional randconfig build errors
> v3:
> - Squash V1 and V2 into one patch
> v2:
> - Fix Kconfig to avoid build errors when LEDS_CLASS_MULTICOLOR is
>    disabled
>
> Aaron Erhardt (2):
>    HID: lamparray: add new LampArray helper module
>    HID: generic: add LampArray support via hid-lamparray helper
>
>   .../ABI/testing/sysfs-driver-hid-lamparray    |  16 +
>   drivers/hid/Kconfig                           |  18 +
>   drivers/hid/Makefile                          |   2 +
>   drivers/hid/hid-generic.c                     |  38 +
>   drivers/hid/hid-lamparray.c                   | 812 ++++++++++++++++++
>   include/linux/hid-lamparray.h                 |  88 ++
>   6 files changed, 974 insertions(+)
>   create mode 100644 Documentation/ABI/testing/sysfs-driver-hid-lamparray
>   create mode 100644 drivers/hid/hid-lamparray.c
>   create mode 100644 include/linux/hid-lamparray.h
>