On 14.02.23 15:59, Hans de Goede wrote: > > On 2/14/23 11:44, Linux regression tracking (Thorsten Leemhuis) wrote: >> Hi, this is your Linux kernel regression tracker. >> >> I noticed a regression report in bugzilla.kernel.org. As many (most?) >> kernel developer don't keep an eye on it, I decided to forward it by >> mail. Quoting from https://bugzilla.kernel.org/show_bug.cgi?id=217026 : >> >>> albimarini4283@xxxxxxxxx 2023-02-12 20:57:03 UTC >>> >>> Brightness control does not work with AMD Ryzen 5800H when using hybrid >>> graphics on kernel updates 6.1.4+. I am using a Lenovo Legion Slim 7 >>> (2021, 15ACH6) currently running Arch Linux with the mainline kernel >>> 6.1.11, however, I have been testing my experience with this issue on >>> every point revision from 6.1.3 to 6.1.11. >>> >>> CPU: AMD Ryzen 5 5800H with Radeon Graphics >>> GPU: NVIDIA RTX 3060 Mobile / Max-Q (Proprietary NVIDIA driver, >>> tested with 525.78.01-1 (version prior to 6.1.4 being released) and >>> 525.89.02-1 (latest driver at time of writing)) >>> System Memory: 40 GB >>> Display: Laptop (Laptop Screen) >>> >>> The only parameters applied at boot on my system are: nvidia-drm.modeset=1 >>> >>> How to reproduce the issue: >>> Enable hybrid graphics/Optimus in BIOS setup. >>> >>> Prior to kernel version 6.1.4, /sys/class/backlight contained two entries: >>> amdgpu_bl0 and nvidia_wmi_ec_backlight >>> >>> With these two entries in /sys/class/backlight , I was able to write to >>> their respective brightness files directly or use a program like light >>> to change the values. Those values would change the brightness of the >>> screen depending on if I was using the AMD GPU or NVIDIA GPU to display >>> the current application. I could set these values to roughly the same >>> thing to achieve an overall complete brightness experience regardless of >>> whether or not I was currently running an application on my integrated >>> (AMD) GPU or dedicated (NVIDIA) GPU. >>> >>> Then, upon updating to kernel versions 6.1.4+, there is no longer an >>> amdgpu_bl0 entry in /sys/class/backlight , just a >>> nvidia_wmi_ec_backlight entry, making it impossible for me to change the >>> brightness on my display when using the iGPU. Interestingly, on kernels >>> 6.1.4+, running "journalctl -b -0 | grep backlight" returns an output >>> "amdgpu: [drm] Skipping amdgpu DM backlight registration", which was not >>> present in prior kernel versions. >>> >>> However, if I instead prepend the option "acpi_backlight=native" to my >>> kernel command line options at boot, "amdgpu_bl0" is once again present >>> in /sys/class/backlight but "nvidia_wmi_ec_backlight" has now >>> disappeared and is nowhere to be seen making it so I can change the >>> brightness when using the iGPU, but the brightness is stuck at max when >>> using the dedicated GPU. Running the above journalctl command at this >>> point returns no errors relating to my AMD GPU and does not mention >>> anything about the NVIDIA GPU. Trying different acpi_backlight options >>> on 6.1.4+ does not fix the issue and instead removes functionality. >>> acpi_backlight=vendor makes an entry called "ideapad" pop up in >>> /sys/class/backlight with nothing else. Changing the brightness values >>> in ideapad does nothing. >>> acpi_backlight=video makes only two entries appear in >>> /sys/class/backlight, acpi_video0 and acpi_video1. Changing the >>> brightness values in either of these directories does nothing. >>> acpi_backlight=none causes nothing to appear under /sys/class/backlight. >>> >>> If hybrid graphics is disabled, the display is connected to the NVIDIA >>> GPU and /sys/class/backlight/nvidia_0 is present, the NVIDIA driver can >>> change the display brightness without a problem.p >>> >>> Below is my lscpi -nn and dmidecode outputs on kernel 6.1.3 and 6.1.11. >>> [...] >> >> See the ticket for more details. >> >> [TLDR for the rest of this mail: I'm adding this report to the list of >> tracked Linux kernel regressions; the text you find below is based on a >> few templates paragraphs you might have encountered already in similar >> form.] >> >> BTW, let me use this mail to also add the report to the list of tracked >> regressions to ensure it's doesn't fall through the cracks: >> >> #regzbot introduced: v6.1.3..v6.1.4 >> https://bugzilla.kernel.org/show_bug.cgi?id=217026 >> #regzbot title: backlight: brightness control stopped working on a Ryzen >> system with hybrid graphics >> #regzbot ignore-activity > > Thank you for forwarding this. yw > I have just added the following comment to the bug: > [...] > Lets continue this inside bugzilla. Thx. FWIW, at least from my side there is no need to post replies to bugzilla and the list; some developers prefer one, some the other -- and regzbot will notice replies to both places. It's IMHO unfortunate that we have to deal with two places, but well, that's how it is. Ciao, Thorsten P.S.: while at it, let me tell regzbot that this one will take some time to get resolved: #regzbot backburner: known bios issue, that why there where tricky aspects beforehand as well; someone from Nvidia is looking into this
