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 A0DB32D5C7A; Thu, 18 Sep 2025 07:33:55 +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=1758180835; cv=none; b=di6uFn9Oo+NAzozaB/HK/qZ9S4ME8q/gU2j+hEDYChC6kQpSAQlyiQUnom/Zo/IL1QMPq5SLnR3rDJy0fkIKrpUf6ZjU/XYtv6bAJNdbw54f5LIE7ZG5bA/+iLH3CUSHLMYeI+xBLAY8xfPzJngomGoUrLO09kmSkpPJ/ZOOsS4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758180835; c=relaxed/simple; bh=zoF2TshriM3ZS0e8AelFve/OPI4XACW7RUZD7luL5+g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=is6SAZAzyp1dNKkqDROU97B8H71BLHhE5IADgdgtvMUExgh4cQPjJhRTM6jXqO5S8oAv2TuEe8GURCjE4jalNbZX+c3Ea4DOWogwXfne9yUUZ2B3nzMIGK+TtgPZTyu1eCzLoaEYVwO/Q2Hhie60UJq15W/Fv16vlH1yoHKsi3o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=r51iA/mc; 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="r51iA/mc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A29A5C4CEE7; Thu, 18 Sep 2025 07:33:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758180835; bh=zoF2TshriM3ZS0e8AelFve/OPI4XACW7RUZD7luL5+g=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=r51iA/mcdivvaemgqGMjjV2SmWFHkPwVzpmTtRhePCYe26CLPkKGj3HcX4F5JlKV5 qDm5FACFLobIj3q/8ZcsJhYH99HHQ2SpNctsDXPmfvb80yT1XQLuRxVamq8E412s87 lcUYjd9mb/ro0e6mBUMkIWaMzD9CE7FP1SvtOxmIRhsA4V2ACK4aU44Acb9lmwsnFR n+QWEXS83Vc8ouvf4je+z/BjXvAHD3EKyRVfYmLPOC6vVnqj2nOox1LNDJtGUsAmQ3 zUKLEIhI0wi2p39tocUMmwELSXL7ogLHXCZChiia8MneNYC7Tot/4qbEKKmAnJ9KpL 6i9OblXcdmSKw== Message-ID: <0b214249-958c-4e14-a4d8-512f1d90dff4@kernel.org> Date: Thu, 18 Sep 2025 09:33:51 +0200 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] ACPI: video: Fix missing backlight node creation on To: Zihuan Zhang Cc: lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, mario.limonciello@amd.com, rafael@kernel.org, stable@vger.kernel.org References: <17cc74d6-2e49-4370-ae37-39cddfe67d7d@kernel.org> <20250912103538.3657242-1-zhangzihuan@kylinos.cn> From: Hans de Goede Content-Language: en-US, nl In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Zihuan, On 18-Sep-25 2:36 AM, Zihuan Zhang wrote: > > 在 2025/9/12 18:35, Zihuan Zhang 写道: >>> 1. There must be a GPU driver for these laptops somewhere? >>> Even if out of tree using a laptop without a GPU these days >>> just does not give a good user experience. So fix the GPU >>> driver to call acpi_video_register_backlight(). >>> >>> Note acpi_video_register_backlight() is deliberately exported >>> without requiring the consuming out of tree kernel module to >>> be GPL to allow this. >>> >>> Other options would be: >>> >>> 2. Add some special heuristics for Zhaoxin CPUs, >>> the kernel already has a CPUID match mechanism for >>> things like this. This could potentially be combined >>> with a DMI system-vendor check to only do this special >>> case handling on e.g. Lenovo and Inspur laptops. >>> >>> 3. Instead of adding the CPU-id based special case >>> just outright use DMI quirks. In this case lets try >>> to use substring matches to cover multiple models >>> with a single entry so as to not grow the quirk >>> table too much. >> >> Got it, thanks! >> >> In fact, we have tried a few approaches (cmdline option, CPU-ID based quirk, and DMI quirk), >> and all of them work. >> I will sync this information with Zhaoxin to see which way they prefer. > > Zhaoxin has confirmed that they will handle this through their own GPU driver. That is good to hear, thank you for the update. Regards, Hans