Created attachment 131413 [details]
dmesg with debug enabled
With 4.12-rc1 the screen goes dark during boot when attempting to modeswitch. I assume the backlight is turned off. Still worked with kernel 4.11. This is on a baytrail tablet.
Bisect would really be helpful here.
Indeed it would, but doing a full bisect takes way too long to compile and test. If you have a list of commits that went into 4.12-rc1 and might be relevant to test I can do a few builds and try those.
Created attachment 131605 [details]
dmesg 4.12-rc3 display on
I tried the 4.12-rc3 to check if anything has changed. Screen still goes dark most of the time. However maybe 1 in 5 boots the screen stays on with full brightness. So this might be a race. Attaching another dmesg of a successful boot with screen staying on.
Did your kernel config change? Possibly dupe of bug 96571. I believe that might manifest itself as a race too.
kernel config stayed the same, no change there.
Any way for me to confirm if this is indeed a dupe of bug 96571?
Also any patches I could test on top of 4.12? I see a lot of patch references in the other bz but not sure what's relevant.
Set config options
and see if it helps.
The only difference to my config was that I had
instead of =y.
However changing those to =y didn't make a difference.
Would any intel-gpu-tools output be useful?
Seeing your comment in bug 96571, can we assume this is a dupe?
(In reply to sassmann from comment #9)
> Yes, correct.
Marking as duplicated. Please keep following the case on 96571 . Thank you.
*** This bug has been marked as a duplicate of bug 96571 ***