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5,420
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✅ Solution
Tags:
display
flicker
grub
Link:
🔍 See Original Answer on Ask Ubuntu ⧉ 🔗
URL:
https://askubuntu.com/q/842991
Title:
Upgrade to 16.10 causes desktop backlight flickering
ID:
/2016/10/28/Upgrade-to-16.10-causes-desktop-backlight-flickering
Created:
October 28, 2016
Edited: June 12, 2020
Upload:
September 15, 2024
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This bug first appeared in bug reports in Kernel version 4.6.2 and users found downgrading to 4.5.4 fixed it. Upgrading to 4.7 did not fix it.
Panel Self Refresh (psr) bug
Links to links to other bug reports say it can be fixed by modifying grub’s kernel boot command line with:
i915.enable_psr=0
To do this you need to gksu gedit /etc/default/grub.
Search for quiet splash and insert i915.enable_psr=0 in front of the last double quote. There may be other options but minimally it should look like this:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.enable_psr=0"
Save the file and type sudo update-grub. Then reboot and the flickering should be gone.
You can read more at: (LCD flickering on Thinkpad T440p (Haswell) with kernel 4.6-rc4 (PSR enabled))
Frame Buffer Compression
At the same time psr was introduced in the 4.6 kernel major revision, fbc (Frame Buffer Compression) support was also introduced. It prevents repainting the screen when it doesn’t change. An imperceptible power savings feature (.06 watts). To turn update the grub kernel command line (as described above) by adding:
i915.enable_fbc=0
The final solution is to turn off i915 mode setting altogether with the grub kernel command line option:
i915.modset=0
Please note these can’t be tested on my system and I can only go by bug reports from users with similar systems to yours.