On Thu, 13 Feb 2014, Luis Ortega <luiorpe1@xxxxxx> wrote: > Hi, testing 3.14-rc2 I noticed I could not adjust the brightness of the > screen any longer. This problem is already present in 3.14-rc1. 3.13 works fine. > > My hardware is a netbook with intel atom and a 945GM graphics card. > > I bisected the problem down to the next commit: I dare say either your bisect went sour or you don't have 945GM. Please verify your steps. Please provide dmesg with drm.debug=0xe with 3.14-rc2. BR, Jani. > > bc0bb9fd1c7810407ab810d204bbaecb255fddde is the first bad commit > commit bc0bb9fd1c7810407ab810d204bbaecb255fddde > Author: Jani Nikula <jani.nikula@xxxxxxxxx> > Date: Thu Nov 14 12:14:29 2013 +0200 > > drm/i915: remove QUIRK_NO_PCH_PWM_ENABLE > > The quirk was added as what I'd say was a stopgap measure in > > commit e85843bec6c2ea7c10ec61238396891cc2b753a9 > Author: Kamal Mostafa <kamal@xxxxxxxxxxxxx> > Date: Fri Jul 19 15:02:01 2013 -0700 > > drm/i915: quirk no PCH_PWM_ENABLE for Dell XPS13 backlight > > without really digging into what was going on. > > Also, as mentioned in the related bug [1], having the quirk regressed > some of the machines it was supposed to fix to begin with, and there > were patches posted to disable the quirk on such machines [2]! > > The fact is, we do need the BLM_PCH_PWM_ENABLE bit set to have > backlight. With the quirk, we've relied on BIOS to have set it, and our > save/restore code to retain it. With the full backlight setup at enable, > we have no place for things that rely on previous state. > > With the per platform hooks, we've also made a change in the PCH > platform enable order: setting the backlight duty cycle between CPU and > PCH PWM enable. Some experimenting and > > commit 770c12312ad617172b1a65b911d3e6564fc5aca8 > Author: Takashi Iwai <tiwai@xxxxxxx> > Date: Sat Aug 11 08:56:42 2012 +0200 > > drm/i915: Fix blank panel at reopening lid > > indicate that we can't set the backlight before enabling CPU PWM; the > value just won't stick. But AFAICT we should do it before enabling the > PCH PWM. > > Finally, any fallout we should fix properly, preferrably without quirks, > and absolutely without quirks that rely on existing state. With the per > platform hooks have much more flexibility to adjust the sequence as > required by platforms. > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=47941 > [2] http://lkml.kernel.org/r/1378229848-29113-1-git-send-email-kamal@xxxxxxxxxxxxx > > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx> > Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx> > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > > > Additionally, when I had narrowed the problem to around 11 commits all the > resulting kernel I compiled made the screen blink and shake from left to right > non-stop. In the -rc kernels this doesn't happen. Thought it was worth > mentioning. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
