Previously reported against Fedora here: https://bugzilla.redhat.com/show_bug.cgi?id=1094066 It seems that the backligt goes dim when the laptop boots. I bisected the kernel, and found that the issue started with the following commit: b35684b8fa94e04f55fd38bf672b737741d2f9e2 is the first bad commit commit b35684b8fa94e04f55fd38bf672b737741d2f9e2 Author: Jani Nikula <jani.nikula@intel.com> Date: Thu Nov 14 12:13:41 2013 +0200 drm/i915: do full backlight setup at enable time We should now have all the information we need to do a full initialization of the backlight registers. v2: Keep QUIRK_NO_PCH_PWM_ENABLE for now (Imre). Signed-off-by: Jani Nikula <jani.nikula@intel.com> Reviewed-by: Imre Deak <imre.deak@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> :040000 040000 0aae5515ca62ff1bfd2e1c2769e30c58b016ffeb 01c2f8cd145f8cf29730908d52e7e89b787a059e M drivers I tested with the latest 3.15-rc kernel (as of 2 nights ago), and it has the same problem.
Created attachment 100119 [details] dmesg from 3.14 kernel dmesg from 3.14 kernel with drm.debug=0xe module parameter set
Created attachment 100120 [details] i915_opregion from 3.14 boot
I saved a copy of all the *brightness* files from under /sys when I booted a 3.13 kernel and compared it to when I booted a 3.14 kerel. The following is the only one that changed: diff -r 3.13.10-200/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight/actual_brightness 3.14.4-200/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight/actual_brightness 1c1 < 255000 --- > 0
Marc, please attach intel_reg_dumper output from the intel-gpu-tools [1] running 1) the bad commit b35684b8fa94e04f55fd38bf672b737741d2f9e2 and 2) the (presumed good) commit immediately before it. Running the good kernel, please also try to change the brightness by echoing to the /sys/class/backlight/intel_backlight/brightness file - does it work as expected? Does the dell_backlight work? [1] http://cgit.freedesktop.org/xorg/app/intel-gpu-tools/
Same bisect result as [1] but I like to keep both of these open as one as opregion and the other doesn't. [1] https://bugzilla.kernel.org/show_bug.cgi?id=75791
Created attachment 100479 [details] Output of intel-gpu-tools for good kernel
Created attachment 100480 [details] Output of intel_reg_dumper for bad kernel With the good kernel, I could change the backlight by echoing values to /sys/class/backlight/intel_backlight/brightness.
Created attachment 100506 [details] [review] drm/i915: set backlight duty cycle after backlight enable for gen4 Please try this patch on top of the bad commit. See if it works and provide the reg dump. Thanks.
Created attachment 100579 [details] Output of intel-gpu-tools for fixed kernel The patch fixes the problem. Thanks for the great work!
(In reply to comment #9) > Created attachment 100579 [details] > Output of intel-gpu-tools for fixed kernel > > The patch fixes the problem. > > Thanks for the great work! Thanks for the report and testing. Patch submitted, I'll close when we get it merged.
commit 6d0cfd569ff908336cbf312e6a211793db843d5a Author: Jani Nikula <jani.nikula@intel.com> Date: Mon Jun 9 18:24:34 2014 +0300 drm/i915: set backlight duty cycle after backlight enable for gen4
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