kabini amdgpu: LVDS not working after resume from suspend (works with radeon)

Submitted by Chí-Thanh Christopher Nguyễn

Assigned to Default DRI bug account

Link to original bug (#101926)

Description

Using Linux 4.12.3 on a netbook with AMD A4-1200 Kabini APU and the amdgpu driver:

Upon resuming from suspend-to-RAM, the LVDS display will become all while.

This situation will persist until a reboot, even after turning it off and on again with xrandr.

Backlight control works fine at all times. External displays (VGA, HDMI) are not affected. The radeon driver does not have this problem.

I noticed that in bug 42960 a very similar issue was fixed in radeon, but am currently unsure whether the fix made it into amdgpu too.