Severe graphical corruption when a second HDMI screen turns on (R600)
I use a Macbook Pro 17" (late 2011) as a desktop with two physical screens attached:
- Notebook's main screen 1920x1200 "LVDS"
- An LG TV connected via DisplayPort -> HDMI cable, 1920x1800 "GSM27"
When the TV turns on, the main screen (1) immediately flickers and corrupts the picture showing shredded ribbons of images from both the main desktop and the secondary TV desktop. Please, see the attached photo.
Turning the TV off immediately returns the main screen to normal operation. When the TV is on and the main screen is corrupted, the secondary desktop on the TV always looks normal. I also noted smaller scale artifacts that look like black frames around windows in cinnamon on the TV. The black frames appear and disappear synchroniously with the main screen corruption.
This bug happens in approx 80% of cases.
Kernel 5.5.17-un-def-alt
$ lspci | grep VGA
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6630M/6650M/6750M/7670M/7690M]