Intel Graphics Flicker Problem (solved)

[mikb]

I have a Lenovo IseaPad S940, with intel graphics (no hybrid graphics). The graphics adapter is reported as:

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00:02.0 VGA compatible controller: Intel Corporation WhiskeyLake-U GT2 [UHD Graphics 620]

The problem I have is that the screen flickers really badly - like it seems more off than on. The problem seems to be worse in X, but once it starts happening, it happens in the consile as well.

I have tried forcing X to use the modesetting driver, but that just hung the system (no errors recorded)

I have tried enable_psr=0 and max_cstates=4 on the kernel command line, also to no avail.

Is anyone able to offer any suggestions?

[Logicien]

A quick search tell me that Linux use the i915 module for you video card. Generally the default kernel parameters are sufficient to make Intel video cards to work. I have many Intel video cards and I put the module in the initramfs to accelerate KMS (Kernel Mode Settings) control of the card.

Some screens have more backlight than others and I have never been able to set the backlight other than with ddccontrol. To replace i915 I ever use efifb. It work properly but I must use fbdev as the Xorg video module and it is less performant than i915 but it work correctly. Critical is video 3D.

[mikb]

It does actually seem to have been a backlight problem. Super annoying, as this glitch has cost me so much productivity.

I found this :https://unix.stackexchange.com/question ... ay-flicker

To cut a long story short, here is my newly modded /etc/X11/xorg.conf.d/20-intel.conf:

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Section "Device"
        Identifier  "Intel Graphics"
        Driver      "intel"
        Option      "AccelMethod"    "sna"
        Option      "TearFree"    "true"
        Option      "BackLight"   "intel_backlight"
EndSection

Seems to have fixed the problem. As you noted, however, brightness adjustment via the function keys doesn't seem to work.

[szatox]

Mikb, I enabled those keys using acpid.
This is the important bit from my /etc/acpi/actions/custom_tpbutton
Copy /etc/acpi/events/default under a new name and modify path inside to whatever you name this script. Obviously, make sure the path to brightness in acpi/actions matches your device too.

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brightness='/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness'
case "$1" in
'button/volumedown' ) amixer set Master 5%- ;;
'button/volumeup' ) amixer set Master 5%+ ;;
'button/f20' ) amixer set Capture toggle ;;
'video/brightnessdown' ) #DISPLAY=':0.0'  xbacklight -dec 5;;
	read br < $brightness
	echo $(($br -1000)) > $brightness ; echo brightness down: $? $br ;;
'video/brightnessup' ) #DISPLAY=':0.0' xbacklight -inc 5;;
	read br < $brightness
	echo $(($br +1000)) > $brightness ; echo brightness down: $? $br ;;
esac