Arch Linux

Wopas32

Member

Registered: 2020-05-24

Posts: 1

Can't change backlight brightness when adding nvidia DRM kernel param.

I was having some problems with a blank screen after returning from supend. After perusing the wiki I found a solution that involved adding "nvidia-drm.modeset=1" to the kernel parameters, which fixed my problem. But after doing that, I cannot change the brightness of my screen even when writing directly to /sys/class/backlight/acpi_video0/brightness. The value in brightness is changing, but the actual brightness stays the same.
I also tried the recommended kernel parameters, but that didn't fix the problem and caused no backlight to be listed under /sys/class/backlight. I want to add that xbacklight doesn't return any errors and modifies the backlight file correctly, it just doesn't change the actual brightness of the screen.

/etc/default/grub:

# GRUB boot loader configuration

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="Arch"
GRUB_CMDLINE_LINUX_DEFAULT="loglevel=3 quiet nvidia-drm.modeset=1"
GRUB_CMDLINE_LINUX=""

# Preload both GPT and MBR modules so that they are not missed
GRUB_PRELOAD_MODULES="part_gpt part_msdos"

# Uncomment to enable booting from LUKS encrypted devices
#GRUB_ENABLE_CRYPTODISK=y

# Set to 'countdown' or 'hidden' to change timeout behavior,
# press ESC key to display menu.
GRUB_TIMEOUT_STYLE=menu

# Uncomment to use basic console
GRUB_TERMINAL_INPUT=console

# Uncomment to disable graphical terminal
#GRUB_TERMINAL_OUTPUT=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE=auto

# Uncomment to allow the kernel use the same resolution used by grub
GRUB_GFXPAYLOAD_LINUX=keep

# Uncomment if you want GRUB to pass to the Linux kernel the old parameter
# format "root=/dev/xxx" instead of "root=/dev/disk/by-uuid/xxx"
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
GRUB_DISABLE_RECOVERY=true

# Uncomment and set to the desired menu colors.  Used by normal and wallpaper
# modes only.  Entries specified as foreground/background.
#GRUB_COLOR_NORMAL="light-blue/black"
#GRUB_COLOR_HIGHLIGHT="light-cyan/blue"

# Uncomment one of them for the gfx desired, a image background or a gfxtheme
#GRUB_BACKGROUND="/path/to/wallpaper"
#GRUB_THEME="/path/to/gfxtheme"

# Uncomment to get a beep at GRUB start
#GRUB_INIT_TUNE="480 440 1"

# Uncomment to make GRUB remember the last selection. This requires
# setting 'GRUB_DEFAULT=saved' above.
#GRUB_SAVEDEFAULT="true"

EDIT:
I've tried quite a lot now so I'm going to list the things that didn't fix the issue:
-Loading the nvidia modules at the earliest possible point using mkinitcpio
-Using kernel parameters like acpi_XXX=XXX like described in other posts with the issue
-Using a different kernel and trying all of the above (tested lts and zen)
-Removing nvidia-drm.modeset=1 from the kernel parameters and trying all of the above in the hopes that my original suspend issue doesn't occur (Fixed the backlight but the suspend-issue occurred again)

Btw., there are no nvidia related error messages during boot, but there are these error messages involving acpi:

[    0.294345] ACPI BIOS Error (bug): Failure creating named object [\_SB.PCI0.XHC.RHUB.HS01._UPC], AE_ALREADY_EXISTS (20200110/dswload2-326)
[    0.294351] ACPI Error: AE_ALREADY_EXISTS, During name lookup/catalog (20200110/psobject-220)
[    0.294353] ACPI: Skipping parse of AML opcode: Method (0x0014

So, I'm kind of at my wits end at this point.

Last edited by Wopas32 (2020-05-25 11:50:42)