Dsi pwm backlight off after hdmi unplugged


no too much change,
just change host1x dc@54240000 to dc@54200000,
so support DP not HDMI from DTS.

plug DP → power on → both DSI/DP display normal → do nothing, just wait → some times → DSI LCD blink.

when LCD blink, dun see dmesg log upadte from ssh.

what was confusing is why DSI+HDMI have no blink?


So you didn’t resolve the pwm issue, you just changed to another usecase, right?

Is it possible to measure/monitoring the pwm value and see if it drops when blink happens?


haven’t got around to research the pwm issue after HDMI unplug.

No use pwm as BL when test DSI+DP using the GPIO as BL.


Then it sounds the gpio does not give stable voltage?

Are you able to monitor it?

Later will do that monitor.

could have some other reasons such as clk … lead to the LCD panel blink ?


I don’t think so. If You use the same mode on DSI between DP and HDMI case, then clk should not br the problem.

tks for your response.
If some update i will note here for share.


One more little question,
is there any flag that can be used to know a monitor pluged?
Also can say how could a process know the monitor’s plug/unplug?



Actually, our DSI driver does not support hotplug, so I think you are talking about DP/HDMI?

If DP/HDMI monitor gets hotplug, the hpd_worker shall print message in dmesg.
You can check dp.c and hdmi2.0.c for this function. DP driver is using function from hpd.c driver but hdmi does not use this file. HDMI has its own detection function in hdmi2.0.c.