I have read this question - Brightness problem on Ubuntu 18.04 and this is my set up -
Linux gansub-OptiPlex-7050 4.15.0-38-generic #41-Ubuntu SMP Wed Oct 10 10:59:38 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
and this is my graphics card -
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 630 (rev 04)
*-display
description: VGA compatible controller
product: Intel Corporation
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
version: 04
width: 64 bits
clock: 33MHz
capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
configuration: driver=i915 latency=0
resources: irq:126 memory:f6000000-f6ffffff memory:e0000000-efffffff ioport:f000(size=64) memory:c0000-dffff
Since yesterday I have screen flickering as well as screen dimness and occasional unable to boot problems. I did a diagnostics check and all tests turned out successful. What usually happens is that the screen starts to flicker, then dim itself and then dies. When I try to reboot it gets stuck. I did try
ubuntu-drivers autoinstall
But the problem persists. Since there maybe so many approaches as per the answers available on this site I would like to know which approach I should take.
EDIT
I made the following change to /etc/default/grub and it is still flickering.
#GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX=""
Based on this Q/A - Ubuntu 18.04 screen strobing here is the output of xrandr
Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1600x900+0+0 (normal left inverted right x axis y axis) 432mm x 236mm
1600x900 60.00*+
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
720x400 70.08
HDMI-3 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
So I am not sure whether I should change the refresh rate to stop the flickering.