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 7767B16132A for ; Tue, 28 Apr 2026 21:23:57 +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=1777411437; cv=none; b=J+MWPeEfYtxw67NlxyXgSlt3YrBHJ68TR4A/b5/V0wgxAe7MeAgdwiy187UhjrWMjPgIzwooK2z3z5zxiLbbP8aNCpv+GylJmqqgsKedyL8IW6Ga7Lovt/XRh9eQQf8fqB5pskYVraVZ29BBGkPgPzik8HsECSLi/B+KPFzCQ+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777411437; c=relaxed/simple; bh=7/c6Rw+TgD9Er8R8X+VKTAKn9zjXITIp29ogNa8yaDM=; h=From:To:Subject:Date:Message-ID:Content-Type:MIME-Version; b=beDFMxIoxj4fqhgub7RNVDGRfkSDMC3P+UCNN4mCdrsEX28A+k1HTgZNv40dGQhyGsneh8R7MBzu/eNyY15qZLsjrOt25XtrLx8Cb+H/m2xBcankU5DEf3rVBstx973/bIb5bx+000uIJn1ud5BX+T6DtCZykn9m9CZ4Ps98juI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZgcrQLHZ; 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="ZgcrQLHZ" Received: by smtp.kernel.org (Postfix) with ESMTPS id 14951C2BCAF for ; Tue, 28 Apr 2026 21:23:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777411437; bh=7/c6Rw+TgD9Er8R8X+VKTAKn9zjXITIp29ogNa8yaDM=; h=From:To:Subject:Date:From; b=ZgcrQLHZLyPDkTCi0QzWixqtstSbfO6m3XHCKYY3Rv9pdVQkDl9PpYSN674C/NBN8 +NJfWltendv4EIhAfCZwPFodHdOSe1zNFTQGr99e3zmys+Pc+owodOm+NimWJnKhzL y9BcGmpr6RWTL3251kBYix8yk7M2Iaf1r+d1E63vK0tWvgnFW+y0NeERwwAaMvHXqo 7H8ioRa6/e066aDu1LaB9lVE26YC7LespikviAWfK8/t/fTehEmXncTolWkVGPQRhT DEbN/ZJiIr9b4T1MmLTtpzyqS91nEIrj3qqh8Gtq9fd3x+G3vkjVppoq/ZLacT1rsu zXeEa4wmvw7JA== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 0BB90C3279F; Tue, 28 Apr 2026 21:23:57 +0000 (UTC) From: bugzilla-daemon@kernel.org To: platform-driver-x86@vger.kernel.org Subject: [Bug 221430] New: nvidia_wmi_ec_backlight: brightness writes silently dropped on HP OMEN 16 (2025) Date: Tue, 28 Apr 2026 21:23:56 +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: floquimaurice@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 cf_kernel_version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter cf_regression attachments.created 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=3D221430 Bug ID: 221430 Summary: nvidia_wmi_ec_backlight: brightness writes silently dropped on HP OMEN 16 (2025) Product: Drivers Version: 2.5 Kernel Version: 6.19.14 Hardware: Intel OS: Linux Status: NEW Severity: normal Priority: P3 Component: Platform_x86 Assignee: drivers_platform_x86@kernel-bugs.osdl.org Reporter: floquimaurice@gmail.com Regression: No Created attachment 309992 --> https://bugzilla.kernel.org/attachment.cgi?id=3D309992&action=3Dedit ACPI tables (DSDT + all SSDTs, raw .dat and disassebled .dsl) Reporting a backlight issue on a recent HP OMEN 16 with hybrid Optimus. # System - HP OMEN by HP Gaming Laptop 16 (2024/2025) - Intel Meteor Lake + NVIDIA RTX 5070 Mobile, NVIDIA driver 595.x - Fedora 44, kernel 6.19.14-300.fc44.x86_64 - Hybrid graphics mode (BIOS) # Symptom nvidia_wmi_ec_backlight loads, sysfs is created, writes to brightness are accepted, but the panel does not respond and actual_brightness returns "No data available". $ echo 50 | sudo tee /sys/class/backlight/nvidia_wmi_ec_backlight/brightn= ess $ cat /sys/class/backlight/nvidia_wmi_ec_backlight/actual_brightness cat: actual_brightness: No data available The AE_AML_OPERAND_VALUE errors visible in dmesg come from hp_bioscfg against \_SB.WMID.* and are unrelated to the backlight path. # What the firmware does The NVIDIA-bound WMAA is at \_SB.PC00.AWMI.WMAA, GUID 603E9613-EF25-4338-A3D0-C46177516DB7. Its write path declares LEDB as the new brightness value from Arg2[4], but never reads it: ElseIf ((MODF =3D=3D One)) { Sleep (0x64) Local1 =3D \_SB.PC00.GFX0.CBL1 /* reads existing value */ Local3 =3D (Local1 * 0x02) If ((Local3 =3D=3D Zero)) { Local3 +=3D 0x02 } \_SB.PC00.LPCB.ECPW =3D Local3 Return (Zero) } The firmware propagates \_SB.PC00.GFX0.CBL1 (which the Windows display driver populates before invoking WMI) to the EC PWM register, instead of using the value the OS driver passed in. Under Linux nothing populates CBL1, so the WMI call returns success but is effectively a no-op. # Attachments - dmesg-clean.txt - dmidecode-clean.txt - acpi-tables-omen16.tar.gz (DSDT + all SSDTs, raw and disassembled) - lspci-full.txt Happy to test patches or provide additional traces. --=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.=