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 A2E2172627 for ; Thu, 4 Jun 2026 19:19:59 +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=1780600799; cv=none; b=qGCxie2t2ejNJ+1E2eZL4Kv2uJ4d5R23W0M8JAQhgzjS2IPTUj0AhjqwfUJG22UasnDNUOipJ76eB0snsUnv2XuWwkwaxJcmXfyZ8B8Z2jposz+8P4M4HpZ8I/W02bI2JYfGifZrh8InBwWjf0kMpkv6eZY5XJPTWzN8IjtO+uY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780600799; c=relaxed/simple; bh=DxEnZ7njPT+OSgKqIOcOUcXlQLIkexxH5XW0AX6otyk=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: Content-Type:MIME-Version; b=CO7v/U/7qwkvhf/HSe+8jEdSujBCIbD9Fx+/AK5KmZoJzcoxMbqbUU2yPs9jZCsjnjVEL6gE5b6hGIuQJbXCtc9wGDlDAsxFan8wCUb5hwt4KDubwA64wasq9MJQzgkoF8IRHH7Aa5Fnetjz3Oh04gLzQrLWmKjWEJIsWjLyqGs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iGHQF7AK; 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="iGHQF7AK" Received: by smtp.kernel.org (Postfix) with ESMTPS id 37274C2BCC7 for ; Thu, 4 Jun 2026 19:19:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1780600799; bh=DxEnZ7njPT+OSgKqIOcOUcXlQLIkexxH5XW0AX6otyk=; h=From:To:Subject:Date:In-Reply-To:References:From; b=iGHQF7AKC/flkK6qKpGVF0QlNWN7xBFl4OaDGs1PjvX6ASs5qx1v5xfzanaBiaDCP mdm0ccv8oiYbkGZeHGVC8ZxvTNH04doyzDLhHwiJxb6SH3yKRHIHYTKJEBDydkU2md pMvyXSw4sQtdOYoVtwnygui9QHyz2Kxzs6auC6BldUUmKbcIKTF3fevpu2SmUs38Zj 9ZCOhRpsA3TBrER2/cr8+AsimdMWzSi5EgjXu1BlZOn2cWHolL/9wYbY9X3JpGc6ME F9nc8hlzAYgRmZLccCAHSzLjMDUyPPd2E+2HSuMtS9PgenXYdSxdnUrYffICEkoYPz dlrj+63lzgOUw== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id 14DB3C41613; Thu, 4 Jun 2026 19:19:59 +0000 (UTC) From: bugzilla-daemon@kernel.org To: platform-driver-x86@vger.kernel.org Subject: [Bug 221583] Lenovo 82KU: keyboard backlight works via Fn+Space but no kbd_backlight LED device exposed Date: Thu, 04 Jun 2026 19:19:58 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed 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: i@rong.moe 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: attachments.created Message-ID: In-Reply-To: References: 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=3D221583 --- Comment #7 from Rong Zhang (i@rong.moe) --- Created attachment 310266 --> https://bugzilla.kernel.org/attachment.cgi?id=3D310266&action=3Dedit DSDT patch Hi George, Thanks for debugging. Based on the information, software control should be possible by overriding the device's DSDT with appropriate ACPI methods prop= erly implemented, which is (unfortunately) not upstreamable. But as the first step, please try writing to the address via /dev/mem and s= ee if the keyboard backlight brightness changes (replace 0xXX with the values = you found): sudo busybox devmem 0xFE00D42A 8 0xXX Writing to EC registers could be dangerous, so please be cautious. I copied and pasted some code from my device's DSDT to create a DSDT patch = for your device. If writing to the address works, you may use it to provide the required ACPI method to ideapad-laptop. I'm not an expert in writing ASL and didn't test it at all, so there is a chance that things could go wrong. Be cautious. See https://www.kernel.org/doc/html/latest/admin-guide/acpi/initrd_table_overri= de.html and https://wiki.archlinux.org/title/DSDT for detailed instructions on overriding DSDT. I'd recommend overriding it using GRUB2. See also https://www.gnu.org/software/grub/manual/grub/html_node/acpi.html If it ain't work, try GRUB_EARLY_INITRD_LINUX_CUSTOM. See https://www.gnu.org/software/grub/manual/grub/html_node/Simple-configuratio= n.html --=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.=