Created attachment 109785 [details] dmesg xset dpms force off leads to a frozen blank screen without any way to recover from it. It happens that on update_status path backlight is disabled before the regular path and it causes this issue. If we avoid "&= ~EDP_BLC_ENABLE;" when coming from backlight_ops.update_status path everything works correctly as expected. For a long time I believed that it was a PSR issue, but when fighting against it I noticed it was happening 100% of the time even with PSR disabled. So I just reproduced and collected log of it on today's nightly that doesn't have PSR for VLV merged yet.
What if you do # echo 4 > /sys/class/backlight/intel_backlight/bl_power # echo 0 > /sys/class/backlight/intel_backlight/bl_power when you're in PSR? Does this reproduce the issue?
Yes, the issue is the same regardless PSR. Yes, this sequence works fine. I also tried echo 4 > /sys/class/backlight/intel_backlight/bl_power echo 4 > /sys/class/backlight/intel_backlight/bl_power echo 0 > /sys/class/backlight/intel_backlight/bl_power to see if disabling it twice would face the issue but no, everything worked correctly. Also I noticed that echo 0 > /sys/class/backlight/intel_backlight/bl_power is the only thing that can restore my screen after I hit the issue. So forget the part of "without any way to recover from it".
Could this be fixed by commit 7ecc778691c452285f754743a93a46fa1d3da52f Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Tue Nov 4 10:36:26 2014 +0000 backlight: bl_power uses 0 for on and 4 for off in the ddx?
Actually the issue happens even when intel_backlight is not present. intel_backlight was actually happening to get display back, but I removed in some compilation and noticed I'm without it and faced blank screen issue again here. So, no ddx patch doesn't fix the issue.
(In reply to Rodrigo Vivi from comment #4) > intel_backlight was actually happening to get display back, but I removed in > some compilation and noticed I'm without it and faced blank screen issue > again here. Do I understand you correctly that this has nothing to do with backlight after all?
Rodrigo, is this still an issue? The dmesg does hint that Ville was on the correct track with comment #3, but if that doesn't help, I'm pretty confused.
Reporter is AWOL, closing. ;) Rodrigo, please reopen if this is still an issue.
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