I have a HP Zbook Fury 15 G7 with Nvidia RTX5000 GPU.
I installed Ubuntu 20.04 LTS
When I resume after suspend, the screen of the laptop display stays black (but pixels are being drawn and updated, it's just extremely dim) the secondary display works fine.
When I press the screen brightness buttons, Ubuntu shows the widget so it's seemingly changing the brightness, but it is not.
When inspecting
/sys/class/backlight/
I found that there is no entry for the Nvidia GPU, ls /sys/class/backlight/
intel_backlight
When I press the screen brightness buttons, the value changes accordingly there
$ cat /sys/class/backlight/intel_backlight/actual_brightness
252
press buttons
$ cat /sys/class/backlight/intel_backlight/actual_brightness
131
The main problem for me is that upon resume, the screen brightness is set at zero for the NVidia card, it resumes fine, but the screen remains black, I can see the login screen very (unusable) dim, If i connect a second screen it pops up fine...
I'm actually hoping that fixing this problem will fix my suspend/resume.
- I tried downgrading nvidia to 460 (back on 470 now)
- I tried the nouveau driver but it constantly glitches, and does not fix the brightness nor sleep problem
- I tried using the intel card, but for some reason that does not fix the problem
[BIG EDIT]
I did some more testing:
I added
Option "RegistryDwords" "EnableBrightnessControl=1"
to usr/share/X11/xorg.conf.d/10-nvidia.conf
I booted with
BOOT_IMAGE=/boot/vmlinuz-5.11.0-37-generic root=UUID=hidden ro quiet splash acpi_backlight=native vt.handoff=7
then I have no /sys/class/backlight entry (besides intel_backlight)
buttons change /sys/class/backlight/intel_backlight/actual_brightness but xbacklight -set 50 does not work (no error, no change of /sys/class/backlight/intel_backlight/actual_brightness
changing grub parameters to
BOOT_IMAGE=/boot/vmlinuz-5.11.0-37-generic root=UUID=hidden ro quiet splash acpi_backlight=video vt.handoff=7
I suddenly have
$ ls /sys/class/backlight
acpi_video0/ acpi_video1/ intel_backlight/
using the brightness keys changes both acpi_video0
$ cat /sys/class/backlight/acpi_video0/actual_brightness
98
pressing button on keyboard>>>
$ cat /sys/class/backlight/acpi_video0/actual_brightness
37
$ cat /sys/class/backlight/acpi_video1/actual_brightness
38
$ cat /sys/class/backlight/acpi_video1/actual_brightness
for some reason there is an offset of 1 between acpi_video0 and acpi_video1 but it is not always reproduceablea nor is it alway +1 or -1 (rounding error?)
$ cat /sys/class/backlight/intel_backlight/actual_brightness
255
intelbacklight stays fixed at 255
changing grub again
BOOT_IMAGE=/boot/vmlinuz-5.11.0-37-generic root=UUID=hidden ro quiet splash acpi_backlight=vendor vt.handoff=7
yields same behaviour as "acpi_backlight=native"
changing grub again
BOOT_IMAGE=/boot/vmlinuz-5.11.0-37-generic root=UUID=hidden ro quiet splash acpi_backlight=video video.use_native_backlight=1 vt.handoff=7
reboot, didn't work
I removed
Option "RegistryDwords" "EnableBrightnessControl=1"
from usr/share/X11/xorg.conf.d/10-nvidia.conf
reboot
changed the video.use_native_backlight=1 to video.use_native_backlight=0
didn't work
reboot
looking at the /sys/class/backlight directory I found that acpi_video0 is actually the nvidia card... it's just not listening
$ ll /sys/class/backlight
total 0
drwxr-xr-x 2 root root 0 Sep 30 14:53 ./
drwxr-xr-x 83 root root 0 Sep 30 14:53 ../
lrwxrwxrwx 1 root root 0 Sep 30 14:53 acpi_video0 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0/
lrwxrwxrwx 1 root root 0 Sep 30 14:53 acpi_video1 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video1/
lrwxrwxrwx 1 root root 0 Sep 30 14:53 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card1/card1-eDP-1/intel_backlight/
I tried switching to the terminal (Ctrl-Alt-F3)
running xbacklight -set 50 returns an XRANDR error but I guess related to the fact that I'm not in X
reboot
BOOT_IMAGE=/boot/vmlinuz-5.11.0-37-generic root=UUID=hidden ro quiet splash acpi_backlight=none video.use_native_backlight=1 vt.handoff=7
is back again missing the /sys/class/backlight/ device links
I did run update-grub after each /etc/default/grub edit, and I verified the boot params with cat /proc/cmdline after each boot
I found out that using xrandr I can change the brightness of the display (of any display) but I also found out in this nvidia post that this is not actually changing the backlight brightness, but rather the pixel gamma before being sent to the display. This means it can never solve my problem (display backlight turned off on resume) at least not for the main laptop display, the secondary display just works fine
the events are being written to the "acpi video device" but the nvidia GPU is not picking them up
$ acpi_listen
video/brightnessdown BRTDN 00000087 00000000 K
video/brightnessup BRTUP 00000086 00000000 K
