Re: [PATCH v4] platform/x86: asus-wmi: Ignore unusable kbd backlight WMI device on ROG Strix G814FP

[Denis Benato <denis.benato@linux.dev>]

12 nov 2026 00:36:34 Moad Tarrih via B4 Relay <devnull+tarrihmoad.proton.me@kernel.org>:

> From: Moad Tarrih <tarrihmoad@proton.me>
>
> On the ASUS ROG Strix G18 G814FP, writing a level to the keyboard
> backlight brightness in sysfs works, but reading it back always gives
> 0, and the read makes the Fn brightness keys misbehave.
>

With "works" do you mean the write report success but does nothing or that it is actually changing the brightness?

I assumed the #1 but from this message it's unclear (to me, and I assume for others as well).

See below.

> The firmware reports the keyboard backlight WMI device as present
> without implementing it, and the backlight is actually driven by
> hid-asus. DSTS(0x00050021) always returns 0x50000, which is level 0

Always returns level zero with the presence bit set.


> regardless of what the actual level is, and every DEVS(0x00050021)
> write is rejected as an unsupported method.
>
> Add a kbd_led_no_wmi quirk that makes asus-wmi treat the keyboard
> backlight WMI device as absent, and set it for this board, matched on
> the DMI board name. asus-wmi then keeps the LED registered for hid-asus
> and no longer reads from or writes to the WMI device.
>
> As a side effect, the kbd_rgb_mode and kbd_rgb_mode_index attributes are
> no longer created on this board, they never worked here since the firmware
> rejects those writes as well.

Isn't this a contraddiction to what is written above? That writes actually succeeds?

>
> Fixes: fac55d29581f ("platform/x86: asus-wmi: Add support for multiple kbd led handlers")
> Suggested-by: Antheas Kapenekakis <lkml@antheas.dev>
> Suggested-by: Denis Benato <denis.benato@linux.dev>
> Cc: stable@vger.kernel.org
> Signed-off-by: Moad Tarrih <tarrihmoad@proton.me>
> Reviewed-by: Antheas Kapenekakis <lkml@antheas.dev>
> ---
> Tested on an ASUS ROG Strix G18 (board G814FP, BIOS G814FP.317) on
> 7.2.14: the brightness attribute reads back the level that was set, the
> Fn keys step from it, and this survives suspend and reboot. W=1 and
> checkpatch --strict are clean. v4 only changes the commit message.
>
> Sercan GOKMEN's B9406CAA patch also adds a field to struct quirk_entry
> and a DMI entry, so whichever lands second may need a trivial rebase.
>
> AI assistance: Claude Code (Claude Opus 5.5) was used to trace the
> asus-wmi code, write the patch and draft the commit message. I reviewed
> it and tested it on the hardware.
> ---
> Changes in v4:
> - Trim the commit message and move the AI assistance note below the
>   --- line (Ilpo).
> - Link to v3: https://patch.msgid.link/20261110-asus-wmi-kbd-readback-v3-1-646adf2b8629@proton.me
>
> Changes in v3:
> - Drop the comment on kbd_led_no_wmi (Antheas).
> - Don't set wmi_backlight_set_devstate for this board: the firmware
>   rejects both DSTS and DEVS on 0x00050012, so the write did nothing
>   (Antheas).
> - Add Antheas's Reviewed-by.
> - Link to v2: https://patch.msgid.link/20261109-asus-wmi-kbd-readback-v2-1-c048fc53d8ee@proton.me
>
> Changes in v2:
> - Add a quirk that makes asus-wmi skip the keyboard backlight WMI
>   device on this board instead of detecting rejected writes at
>   runtime (Antheas), so no more WMI writes that are known to fail
>   are issued (Denis).
> - Link to v1: https://patch.msgid.link/20261108-asus-wmi-kbd-readback-v1-1-bf38f6400ade@proton.me
> ---
> drivers/platform/x86/asus-nb-wmi.c | 13 +++++++++++++
> drivers/platform/x86/asus-wmi.c    |  3 ++-
> drivers/platform/x86/asus-wmi.h    |  1 +
> 3 files changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/asus-nb-wmi.c b/drivers/platform/x86/asus-nb-wmi.c
> index 3b0f3346dc60..9b2a4b829885 100644
> --- a/drivers/platform/x86/asus-nb-wmi.c
> +++ b/drivers/platform/x86/asus-nb-wmi.c
> @@ -93,6 +93,10 @@ static struct quirk_entry quirk_asus_unknown = {
>     .wmi_backlight_set_devstate = true,
> };
>
> +static struct quirk_entry quirk_asus_g814fp = {
> +   .kbd_led_no_wmi = true,
> +};
> +
> static struct quirk_entry quirk_asus_q500a = {
>     .filter_i8042_e1_extended_codes = true,
>     .wmi_backlight_set_devstate = true,
> @@ -167,6 +171,15 @@ static int dmi_matched(const struct dmi_system_id *dmi)
> }
>
> static const struct dmi_system_id asus_quirks[] = {
> +   {
> +       .callback = dmi_matched,
> +       .ident = "ASUS ROG Strix G18 G814FP",
> +       .matches = {
> +           DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
> +           DMI_MATCH(DMI_BOARD_NAME, "G814FP"),
> +       },
> +       .driver_data = &quirk_asus_g814fp,
> +   },
>     {
>         .callback = dmi_matched,
>         .ident = "ASUSTeK COMPUTER INC. Q500A",
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index b33ebdb21aa2..51fea21ff247 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -2165,7 +2165,8 @@ static int asus_wmi_led_init(struct asus_wmi *asus)
>     asus->kbd_led.brightness_set_blocking = kbd_led_set;
>     asus->kbd_led.brightness_get = kbd_led_get;
>     asus->kbd_led.max_brightness = ASUS_EV_MAX_BRIGHTNESS;
> -   asus->kbd_led_avail = !kbd_led_read(asus, &led_val, NULL);
> +   asus->kbd_led_avail = !asus->driver->quirks->kbd_led_no_wmi &&
> +                 !kbd_led_read(asus, &led_val, NULL);
>     INIT_WORK(&asus->kbd_led_work, kbd_led_update_all);
>
>     if (asus->kbd_led_avail) {
> diff --git a/drivers/platform/x86/asus-wmi.h b/drivers/platform/x86/asus-wmi.h
> index b45f81b38a47..e53c6b3fc619 100644
> --- a/drivers/platform/x86/asus-wmi.h
> +++ b/drivers/platform/x86/asus-wmi.h
> @@ -41,6 +41,7 @@ struct quirk_entry {
>     bool wmi_force_als_set;
>     bool wmi_ignore_fan;
>     bool filter_i8042_e1_extended_codes;
> +   bool kbd_led_no_wmi;
>     int key_wlan_event;
>     enum asus_wmi_tablet_switch_mode tablet_switch_mode;
>     int wapf;
>
> ---
> base-commit: c339f4010dea8b0d754f84ace70cd1b089878ef8
> change-id: 20261108-asus-wmi-kbd-readback-236245e82de8
>
> Best regards,
> -- 
> Moad Tarrih <tarrihmoad@proton.me>