[PATCH v3] platform/x86: asus-wmi: Ignore unusable kbd backlight WMI device on ROG Strix G814FP

[PATCH v3] platform/x86: asus-wmi: Ignore unusable kbd backlight WMI device on ROG Strix G814FP

[Moad Tarrih via B4 Relay]

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.

The firmware reports the keyboard backlight WMI device as present but
doesn't implement it. DSTS(0x00050021) always returns 0x50000, which
is level 0 regardless of what the actual level is, and every
DEVS(0x00050021) write is rejected as an unsupported method. The
keyboard backlight is actually driven by hid-asus. asus-wmi saves the 0
as the current level on every read, and the brightness keys step from
the saved level. So after any read, for example by the desktop or by
systemd-backlight, the brightness-up key sets the keyboard to the
lowest level instead of one step higher.

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.

With its own quirk entry, the board no longer gets
wmi_backlight_set_devstate from the default quirk_asus_unknown. That
flag makes asus-wmi write DEVS(0x00050012, 2) at probe, but this
firmware rejects both DSTS and DEVS on 0x00050012 as unsupported
methods, so the write never did anything here.

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.

This patch was written with the help of an AI coding assistant (Claude
Code, Claude Opus 5.5). I reviewed it and tested it on my affected laptop.

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,
keyboard 0b05:19b6) on 7.2.14, built as DKMS modules. The keyboard
backlight is still registered and driven by hid-asus, the attribute
reads back the level that was set, the brightness keys step from the
real level, and the level survives suspend/resume and reboots. v3
was retested the same way, and the screen backlight
(nvidia_wmi_ec_backlight) still works without
wmi_backlight_set_devstate.
Build-tested with W=1 against pdx86 for-next (c339f4010dea): no
warnings. checkpatch --strict is clean.

The kbd_rgb_mode and kbd_rgb_mode_index attributes are no longer
created on this board. They never worked here: writes to kbd_rgb_mode
are rejected by the firmware with -ENODEV, like the brightness writes.

To answer Denis's questions on v1, the bug this patch fixes happens on
the latest BIOS for this board as of writing, which is version 317.
I only have the G814FP, so I don't know if other 2025 G814 models
are affected, the quirk only matches G814FP.

This no longer depends on Sercan GOKMEN's kbd_led_no_readback patch.
Both patches add a field to struct quirk_entry and a DMI entry, so
whichever lands second may need a trivial rebase.

AI assistance: Claude Code was used to trace the keyboard backlight
code in asus-wmi, run the debugfs DSTS/DEVS probes, write the patch and
draft this message. Testing and final review were done by me on the
hardware.
---
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>

Re: [PATCH v3] platform/x86: asus-wmi: Ignore unusable kbd backlight WMI device on ROG Strix G814FP

[Ilpo Järvinen]

On Tue, 10 Nov 2026, Moad Tarrih via B4 Relay wrote:

> 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.
> 
> The firmware reports the keyboard backlight WMI device as present but
> doesn't implement it. DSTS(0x00050021) always returns 0x50000, which
> is level 0 regardless of what the actual level is, and every
> DEVS(0x00050021) write is rejected as an unsupported method. The
> keyboard backlight is actually driven by hid-asus.

> asus-wmi saves the 0
> as the current level on every read, and the brightness keys step from
> the saved level. So after any read, for example by the desktop or by
> systemd-backlight, the brightness-up key sets the keyboard to the
> lowest level instead of one step higher.

This seems just unnecessary fluff. LLMs tends to overword changelogs, 
please be mindful with that when reviewing the output you got from LLM.

> 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.
> 
> With its own quirk entry, the board no longer gets
> wmi_backlight_set_devstate from the default quirk_asus_unknown. That
> flag makes asus-wmi write DEVS(0x00050012, 2) at probe, but this
> firmware rejects both DSTS and DEVS on 0x00050012 as unsupported
> methods, so the write never did anything here.

I think this paragraph too just makes changelog longer for no reason.

> 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.
> 
> This patch was written with the help of an AI coding assistant (Claude
> Code, Claude Opus 5.5). I reviewed it and tested it on my affected laptop.

Notes on how a patch was prepared belong under --- line.

> 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,
> keyboard 0b05:19b6) on 7.2.14, built as DKMS modules. The keyboard
> backlight is still registered and driven by hid-asus, the attribute
> reads back the level that was set, the brightness keys step from the
> real level, and the level survives suspend/resume and reboots. v3
> was retested the same way, and the screen backlight
> (nvidia_wmi_ec_backlight) still works without
> wmi_backlight_set_devstate.
> Build-tested with W=1 against pdx86 for-next (c339f4010dea): no
> warnings. checkpatch --strict is clean.
> 
> The kbd_rgb_mode and kbd_rgb_mode_index attributes are no longer
> created on this board. They never worked here: writes to kbd_rgb_mode
> are rejected by the firmware with -ENODEV, like the brightness writes.
> 
> To answer Denis's questions on v1, the bug this patch fixes happens on
> the latest BIOS for this board as of writing, which is version 317.
> I only have the G814FP, so I don't know if other 2025 G814 models
> are affected, the quirk only matches G814FP.
> 
> This no longer depends on Sercan GOKMEN's kbd_led_no_readback patch.
> Both patches add a field to struct quirk_entry and a DMI entry, so
> whichever lands second may need a trivial rebase.
> 
> AI assistance: Claude Code was used to trace the keyboard backlight
> code in asus-wmi, run the debugfs DSTS/DEVS probes, write the patch and
> draft this message. Testing and final review were done by me on the
> hardware.
> ---
> 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>
> 
> 

-- 
 i.