(Mixed Display Port and HDMI) dual monitors will not go to sleep (Manjaro KDE) – SOLUTION
by Logan Rogers-Follis on May.04, 2023, under Linux, Techie
Mostly posting this here to help me keep track of the bug.
Looks like on AMD GPUs have and ongoing bug when you have a monitor using HDMI to connect to the onboard (iGPU) or add-in GPU, where the monitor going into “Input Scan” will causing the computer to wake back up the other monitors and they never turn off. There are some workarounds (none work for me), but ultimately it needs fixed or I need to get away from an HDMI connection to my secondary monitor.
Freedesktop.org’s gitlab issues tracker: HDMI connected monitors fail to sleep and instead turn back on when amdgpu.dc=1
SOLUTION (workaround): is to pickup a Display Port to DVI (computer to Monitor) adapter and stop using the HDMI input. In this case once the screens go to sleep the monitor will still go into an “Input Scan” mode, but when no other input is found the monitor will go back to DVI and go to sleep correctly. I was able to test this without waiting for the Monitor Sleep timer to be reached with the following command from the Konsole – “xset dpms force standby”
