Re: [BUG] Input: atkbd: REDMI Book Pro 14 2026 (TM2426) needs dumbkbd workaround

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Jame,

On Fri, Oct 16, 2026 at 01:41:19PM -0500, Jame Jao wrote:
> Hi Dmitry and linux-input,
> 
> I would like to report a built-in keyboard compatibility issue on the
> Xiaomi REDMI Book Pro 14 2026 (TM2426).
> 
> Original failure, observed on Arch Linux 7.2.8-zen1-2-zen:
> The internal keyboard could not be used after Linux booted; an external
> USB keyboard was needed. Adding i8042.dumbkbd=1 made it usable.
> 
> Current verification (2026-10-17):
> The machine still boots with i8042.dumbkbd=1. The built-in device is
> "AT Translated Set 2 keyboard", isa0060/serio0/input0, with EV=100013
> and no EV_LED capability. There is no input Caps Lock LED interface.
> I understand the missing LED interface is an expected consequence of
> dumbkbd, rather than a separate LED regression. A local userspace
> workaround writes SETLEDS through /dev/port; it is not an input driver fix.
> 
> Hardware:
>   sys_vendor: XIAOMI
>   product_name: REDMI Book Pro 14 2026
>   board_name: TM2426
>   BIOS: RMAPT4B0P0909, 05/21/2026
>   EC firmware: 1.9
>   CPU: Intel Core Ultra 5 338H
> 
> Current kernel:
>   Linux 7.2.9-zen1-1.1-zen, x86_64
>   Arch package linux-zen 7.2.9.zen1-1.1
> 
> This is a locally built zen kernel with a small bitland-mifs-wmi
> suspend/resume error-handling change only. No atkbd/i8042 or graphics
> change was made in that local patch. Kernel taint is 576 (U and W);
> unsafe xe options and an intel_bios_init warning are also present.
> 
> The current upstream atkbd.c DMI table, inspected on 2026-10-17, has
> atkbd_deactivate_fixup entries for Xiaomi Book Pro 14 (TM2424) and
> REDMI Book Pro 16 2026 (TM2425), but no matching product entry for this
> 14-inch REDMI model. This suggests the same quirk might be applicable,
> but that is only a hypothesis: I have NOT tested that change on TM2426.
> 
> Source inspected:
> https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux/+/refs/heads/master/drivers/input/keyboard/atkbd.c
> 
> Limitations:
> I have not repeated a boot without dumbkbd during this reporting session,
> and have not reproduced the original failure on current mainline or
> drm-tip. The original no-workaround failure above is historical; the
> current device capability and DMI information were checked again today.
> Please do not treat this as a tested patch or a Tested-by statement.
> 
> Could you advise whether testing atkbd_deactivate_fixup for this DMI
> product is the appropriate next step, and what diagnostic data would
> be useful?

Yes, can you please try adding a quirk similar to TM2425 and let us know
if this solves the issue for you? Then we can include it in the kernel.

Thanks.

-- 
Dmitry