From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 611A4396D14 for ; Tue, 24 Feb 2026 15:43:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771947818; cv=none; b=VeYyKg7frl5Gfevmn58cXzsZdc9x+RnLjPoIUY39hIZvSTTr7uNdoUZFLf14PIdz0THVcvHKAOWaZ3zEnQxrBN3WeB/kFHe28Tt4Pi2XOoF7xMOAQtNNyW6SQN/LTPrbMGa24N8hiQMdb83lra7FtuntTzvhNaBfSOM35zVxWF8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771947818; c=relaxed/simple; bh=WRV3mPzePWOz5LDtIMXaDNNP9F7G/JBRcfLuawgcihc=; h=From:To:Subject:Date:Message-ID:Content-Type:MIME-Version; b=CFaEpsKXPZaZEQ2luD9+G42d14We9YFSCeL/mISNLDSqTuVPouSErYkwQCEKzthuZ75Ntjz7EHgcS4BjMj4I1xiRWnx7sE8Mwib4PnWabzDZURPAlraNAZIEhn936MmjgbiqPCCD5aM5bQfXlRpNXmLdwM93YIKxDaG5UifTdx0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u0mxIUjO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u0mxIUjO" Received: by smtp.kernel.org (Postfix) with ESMTPS id 07155C116D0 for ; Tue, 24 Feb 2026 15:43:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771947818; bh=WRV3mPzePWOz5LDtIMXaDNNP9F7G/JBRcfLuawgcihc=; h=From:To:Subject:Date:From; b=u0mxIUjOteY+jG47XL5atIQ1sC5LiwaUCgfEE3HCcKO+b5SvvDJou7IcdHOYF+HGT pikFHVX1jiKoZ7VRY4RWo2s1nOWE5pTmtLlYRn6YpP3q59UmhNR3RlQ0Y646CoU1Pz usneT2BQv5LCrY/y934Jcun57+sRj/8Kaq3VwLx+RHmL1vvbt+OC/xZGuukeQuUpBo /saHU74ZMj0OMtIv66R9o5RZUN0MP3wIZaXh4ivwVYhh5dcZDMhKaAwaVoLEPeixnh hY+BkFRQY9W7rfsBNU3tYZhmXMfWFBvq1ud056G6Thx7l5JkEgzSylMwUUkYj+3sSB IEeTMDdSFXZQw== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 01D68C41613; Tue, 24 Feb 2026 15:43:38 +0000 (UTC) From: bugzilla-daemon@kernel.org To: platform-driver-x86@vger.kernel.org Subject: [Bug 221133] New: asus-wmi: keyboard backlight not detected on ASUS Zenbook S 14 UX5406SA due to KBLC flag not set in BIOS Date: Tue, 24 Feb 2026 15:43:37 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: AssignedTo drivers_platform_x86@kernel-bugs.osdl.org X-Bugzilla-Product: Drivers X-Bugzilla-Component: Platform_x86 X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: keithpsu03@gmail.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: drivers_platform_x86@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter cf_regression Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated Precedence: bulk X-Mailing-List: platform-driver-x86@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D221133 Bug ID: 221133 Summary: asus-wmi: keyboard backlight not detected on ASUS Zenbook S 14 UX5406SA due to KBLC flag not set in BIOS Product: Drivers Version: 2.5 Hardware: Intel OS: Linux Status: NEW Severity: normal Priority: P3 Component: Platform_x86 Assignee: drivers_platform_x86@kernel-bugs.osdl.org Reporter: keithpsu03@gmail.com Regression: No System: =E2=80=A2 Device: ASUS Zenbook S 14 UX5406SA =E2=80=A2 Board: UX5406SA =E2=80=A2 BIOS: UX5406SA.308 (06/05/2025) =E2=80=A2 Kernel: 6.17.0-14-generic (Ubuntu) =E2=80=A2 Platform: Intel Lunar Lake Bug: The asus-wmi driver does not create asus::kbd_backlight on this laptop, even though the keyboard backlight hardware works. GNOME cannot display a bright= ness OSD or manage auto-timeout on inactivity. Root cause: The WMI DSTS handler for ASUS_WMI_DEVID_KBD_BACKLIGHT (0x00050021) calls th= e EC method GLKB(1), which checks KBLC & 0x80. On this laptop, the BIOS does not= set bit 7 of the KBLC ACPI variable, so GLKB(1) returns 0, and the driver's kbd_led_init() sees -ENODEV from asus_wmi_get_devstate_simple(). However, the DEVS handler for 0x00050021 calls SLKB() unconditionally (no K= BLC check), and the hardware responds correctly: # Confirm GLKB(1) returns 0 (backlight reported as not present): echo "\_SB.PC00.LPCB.EC0.GLKB 1" > /proc/acpi/call cat /proc/acpi/call # Result: 0x0 # But calling SLKB directly turns on the backlight: echo "\_SB.PC00.LPCB.EC0.SLKB 0x83" > /proc/acpi/call cat /proc/acpi/call # Result: 0x1 (success, backlight turns on) Relevant DSDT excerpts (BIOS UX5406SA.308): KBLC is an 8-bit field in the AECO SystemMemory region: OperationRegion (AECO, SystemMemory, AECB, 0x1F) Field (AECO, AnyAcc, NoLock, Preserve) { AECS, 32, ACPF, 8, DCPF, 8, TPSV, 8, TCRT, 8, PPSV, 8, DSYN, 8, WOLO, 8, EGBF, 32, KBLC, 8, // <-- bit 7 gates kbd backlight presence KBLV, 8, ... } GLKB (get keyboard backlight state): Method (GLKB, 1, NotSerialized) { If ((Arg0 =3D=3D One)) { Local0 =3D (KBLC & 0x80) If (Local0) { Return (One) } Else { Return (Zero) } // <-- always hits this path } ElseIf ((Arg0 =3D=3D 0x02)) { Return (KBLV) } ElseIf ((Arg0 =3D=3D 0x03)) { Return (0x80) } Return (Ones) } SLKB (set keyboard backlight) =E2=80=94 works unconditionally: Method (SLKB, 1, NotSerialized) { KBLV =3D (Arg0 & 0x7F) If ((Arg0 & 0x80)) { Local0 =3D DerefOf (PWKB [KBLV]) } Else { Local0 =3D Zero } ST9E (0x1F, 0xFF, Local0) Return (One) } Additional context: An earlier unit of this same model (before RMA replacement) had the keyboard backlight working correctly under Linux, suggesting a BIOS update removed or broke the KBLC bit 7 initialization. Proposed fix: Add a DMI quirk for the UX5406SA that skips the KBLC presence check and for= ces keyboard backlight support, since the hardware and SLKB setter work correct= ly regardless. Something like: static const struct dmi_system_id asus_wmi_force_kbd_backlight[] =3D { { .matches =3D { DMI_MATCH(DMI_BOARD_NAME, "UX5406SA"), }, }, { } }; And in kbd_led_init(), if the DMI matches, proceed with backlight setup eve= n if asus_wmi_get_devstate_simple() returns -ENODEV. Workaround: Using acpi_call to directly invoke SLKB: modprobe acpi_call echo "\_SB.PC00.LPCB.EC0.SLKB 0x83" > /proc/acpi/call --=20 You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.=