From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from wp530.webpack.hosteurope.de (wp530.webpack.hosteurope.de [80.237.130.52]) (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 4906E2CA2 for ; Mon, 31 Jan 2022 06:36:29 +0000 (UTC) Received: from ip4d173d02.dynamic.kabel-deutschland.de ([77.23.61.2] helo=[192.168.66.200]); authenticated by wp530.webpack.hosteurope.de running ExIM with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) id 1nEQIc-0004Ov-L4; Mon, 31 Jan 2022 07:36:27 +0100 Message-ID: <74ee2216-a295-c2b6-328b-3e6d0cc1847e@leemhuis.info> Date: Mon, 31 Jan 2022 07:36:26 +0100 Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Content-Language: en-BS From: Thorsten Leemhuis To: "regressions@lists.linux.dev" Subject: Intel_backlight does not work after updating from 5.10.89 to latest 5.15.17 (fwd from bugzilla) Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-bounce-key: webpack.hosteurope.de;regressions@leemhuis.info;1643610989;f6984e3a; X-HE-SMSGID: 1nEQIc-0004Ov-L4 Hi, this is your Linux kernel regression tracker speaking. There is a regression in bugzilla.kernel.org I'd like to add to the tracking: #regzbot introduced: v5.10.89..v5.15.17 #regzbot from: Filippo Falezza #regzbot title: backlight: Intel_backlight does not work after updating from 5.10.89 to latest 5.15.17 #regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=215553 Quote: > As per title, after updating the kernel from to the currently latest version available in Arch repositories, the intel_backlight class has stopped working. > > This is still present under /sys/class/backlight, but any change to it does not affect backlight. The only change that can be made is by setting abcklight to 0, which turns off the screen. > > To keep a usable system, I had to roll-back to 5.10.89, the last known version to work properly. > > I have tried changing the pwm of the screen, which does affect the backlight, dimming it in steps, but it seems that something major has been changed. > I also tried to just roll back the linux-firmware package, with no success. From this, I concluded that the issue should be in the kernel. > > Finally, I should say that I have noticed a change in the scale of intel_backlight, as maximum_backlight went from 120000 down to 512. > > Thanks to anyone who will help me. > > > Which files should I upload to start debugging? Ciao, Thorsten