Arch Linux

punkrockguy318

Member

From: New Jersey

Registered: 2004-02-15

Posts: 711

Website

No Backlight Control on Dell G15 with amd gpu and nvidia 3060

I've recently acquired a Dell G15 laptop that has amd integrated graphics and a nvidia RTX 3060 card.  By default, the laptop uses nVidia Optimus for GPU switching, which can toggled in the BIOS. Besides backlight control, everything seems to work out of the box with nvidia and nvidia-prime installed.  The integrated amdgpu driver is used, but the nvidia card is available when launching applications with "prime-run".  This can be confirmed with glxinfo output:

$ glxinfo | grep "OpenGL"
OpenGL vendor string: AMD
OpenGL renderer string: AMD RENOIR (DRM 3.40.0, 5.10.54-1-lts, LLVM 12.0.1)

$ prime-run glxinfo | grep "OpenGL"
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: NVIDIA GeForce RTX 3060 Laptop GPU/PCIe/SSE2
OpenGL core profile version string: 4.6.0 NVIDIA 470.57.02
OpenGL core profile shading language version string: 4.60 NVIDIA

My main issue is that the backlight is set to maximum and cannot be adjusted when Optimus is enabled. I see that /sys/class/backlight is populated with "amdgpu_bl1", but this backlight does not seem to control the backlight. KDE and other desktop environments will change the value of /sys/class/backlight/amdgpu_bl1/backlight but this does not change the backlight level of the monitor.

If I disable optimus in the BIOS settings (which makes the laptop only use the nvidia card), backlight control does work and /sys/class/backlight is populated with a "nvidia_0" directory that does control the backlight.  Unfortunately, I haven't been able to get /sys/class/backlight/nvidia_0 to appear when Optimus is enabled.

I've tried different combinations of these different kernel parameters to try to get linux to use nvidia_0 instead of amdgpu_bl1 for backlight control, but none of these have seemed to work:

nvidia.NVreg_EnableBacklightHandler=1
acpi_backlight=vendor
acpi_backlight=video
acpi_backlight=native
acpi_backlight=none
acpi_backlight=nvidia
acpi_osi=linux

I've also tried a (slightly modified to allow for compilation) version of nvidia-bl-dkms from AUR (https://aur.archlinux.org/packages/nvidia-bl-dkms/), but it claims that the hardware is not available.

I've also tried optimus-manager, but this doesn't change how the backlight controls are presented in /sys/class/backlight

Does anyone else have a ryzen laptop with a discrete nvidia graphics card that has run into a similar issue? Or does anyone have any ideas of anything else to try? Currently I can only adjust the brightness in linux if I disable optimus completely in the BIOS.  I'd love to gather some info about this in this thread. Thanks!

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If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but have not love, I am nothing.   1 Corinthians 13:2

ThatMan

Member

From: Ontario, Canada

Registered: 2021-07-29

Posts: 2

Re: No Backlight Control on Dell G15 with amd gpu and nvidia 3060

Driver 470.57 has a backlight issue, it seem to have been present since the 465.x set of drivers.

My fix was to downgrade my kernel to 5.12.9 and downgrade the nvidia drivers to 460.67

I used the fixes from here: https://bbs.archlinux.org/viewtopic.php?id=230932

https://forums.developer.nvidia.com/t/l … /175585/18

punkrockguy318

Member

From: New Jersey

Registered: 2004-02-15

Posts: 711

Website

Re: No Backlight Control on Dell G15 with amd gpu and nvidia 3060

Driver 470.57 has a backlight issue, it seem to have been present since the 465.x set of drivers.

My fix was to downgrade my kernel to 5.12.9 and downgrade the nvidia drivers to 460.67

I used the fixes from here: https://bbs.archlinux.org/viewtopic.php?id=230932

https://forums.developer.nvidia.com/t/l … /175585/18

Thanks for the info, thatman - that's very helpful to see that other people are in the same (or similar) situation.
I tried kernel 5.12.9 with nvidia 460.67-1, but I'm still having the same issue.  Can you confirm the linux command line you are using?  When I use "quiet pcie_aspm=force acpi_osi=" from the thread you mentioned (https://bbs.archlinux.org/viewtopic.php?id=230932), linux hangs on boot

Last edited by punkrockguy318 (2021-07-31 00:51:36)

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If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but have not love, I am nothing.   1 Corinthians 13:2

ThatMan

Member

From: Ontario, Canada

Registered: 2021-07-29

Posts: 2

Re: No Backlight Control on Dell G15 with amd gpu and nvidia 3060

I can confirm those are the kernel parameters that I'm running.

If its hanging you can you re doing the other kernel parameter that you've already tried.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,657

Re: No Backlight Control on Dell G15 with amd gpu and nvidia 3060

If you're running in Optimus/PRIME mode the nvidia card should be irrelevant for backlight control and you need to find out why amdgpu doesn't allow to control the backlight

maraud514

Member

Registered: 2021-09-06

Posts: 1

Re: No Backlight Control on Dell G15 with amd gpu and nvidia 3060

I am also having this issue on my Dell G15 ryzen 5800H / rtx 3060 on manjaro. I feel like I have tried everything and read every thread on the subject.. I am running kernel 5.14 and nvidia driver 470 as of right now.
Does anyone manage to fix this issue?
As a temporary workaround I am using xrandr --output eDP --brightness 1. Values can be between 0 and 1.

Thanks

mhalano

Member

Registered: 2022-08-12

Posts: 1

Re: No Backlight Control on Dell G15 with amd gpu and nvidia 3060

I have a Dell G15 5511 with an Intel processor instead of a AMD one and just `acpi_backlight=video` worked for me.