Displays

Suspending & Waking up

• I had an issue with a ViewSonic monitor connected to an HDMI matrix where the display would not wake up after sleep. I had to turn off and on the monitor to get the display back. It was fixed completely by turning off in the monitor's settings the option "Auto-Detect".

Screen Tearing

• On modern hardware there seems to be many options to remove screen tearing entirely:
  • HDMI starting with version 2.1 has an extension called VRR (Variable Refresh Rate) that seems to take care of the problem. But this requires both an HDMI 2.1 capable monitor and an HDMI video card (only very recent nvidia cards from 2020 have that).
  • AMD has FreeSync but it requires an AMD card (Radeon).
  • Nvidia has G-sync but is quite useless as it needs a monitor supporting G-sync. Almost no monitor does because G-sync require a special hardware module, whereas they all support FreeSync since FreeSync is free.
  • Nvidia finally started supporting FreeSync on most monitors but it requires a DisplayPort cable since in fact it uses a DisplayPort technology for VRR (whereas AMD cards can do it over HDMI, even without HDMI 2.1). Nvidia probably won't be able to add support for FreeSync over HDMI.
  • For HDMI TVs, no solution except HDMI 2.1.

• If you cannot use a hardware solution (mostly it means using an nvidia card connected to a monitor by HDMI), you have to resort to software Vertical Sync. See for instance this article for screen tearing / vertical sync on KDE#KDE_Compositor_and_Vertical_Sync.

Testing Screen Tearing

• This is a good URL for checking screen tearing in Chromium: https://www.youtube.com/watch?v=DaBQ3hCJxpE.
• Moving around windows very quickly is also an efficient way of testing tearing on the desktop environment.
• There are also downloadable movies for checking movie players (available for instance at http://silverlinux.blogspot.com/2013/05/vsync-test-videos.html).