Reported by ~nullmark in the chat:
I just noticed that the screenlock display off mode does not actually turns the screen off. Just the backlight is off, the screen stays on. Can be verified with a bright light source.
This seems to cause some burn-in, that does fade away with time again.
The problem can be mitigated if we adapt sxmo_screenlock to just open a black window (unless someone knows a better solution to actually power down the display).
~singpolyma suggests a white window, I'm not sure I get why:
should set to all white not all black. will turn off all the lcd pixels and save power
LCD pixels consume a small amount of power to stay in a non-resting state. I was not able to find a datasheet for the PinePhone display to check whether it is normally white or normally black, or how much power is consumed.
A white overlay may well be better for power, only we would need to ensure the X server has closed the window and redrawn the screen before raising the baclkight to avoid flashbangs.
I have just implemented this in patch https://lists.sr.ht/~mil/sxmo-devel/patches/19920 and have indeed attempted to make sure there are as few as possible 'flashbangs'.
xset dpms force offworks to turn it off completely.Backlight @ 0% AND written 0 to
/sys/class/backlight/backlight/bl_powerBattery full in 10h 00min (delivering 54 mAh)
Battery full in 11h 01min (delivering 49 mAh)
Battery full in 11h 37min (delivering 49 mAh)
// xset dpms force off
Battery full in 03h 26min (delivering 157 mAh)
Battery full in 03h 53min (delivering 139 mAh)
Battery full in 03h 29min (delivering 155 mAh)
The powerdraw during screenlock went from ~530mAh to ~350mAh after adding
xset dpms force off!Big win for battery life while listening to music!
Oh! That is great news indeed! Thanks for the test, I will definitely implement this for next release then!
new version of the patch: https://lists.sr.ht/~mil/sxmo-devel/patches/19955