[Bug 67950] New: [ivb regression] 3.10: i915 blanks eDP panel (backlight set to 0 and further ineffective)

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=67950

          Priority: medium
            Bug ID: 67950
                CC: kirill at shutemov.name, vsu at altlinux.org
          Assignee: intel-gfx-bugs at lists.freedesktop.org
           Summary: [ivb regression] 3.10: i915 blanks eDP panel
                    (backlight set to 0 and further ineffective)
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: mike at altlinux.org
               URL: https://bugzilla.altlinux.org/29219
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: XOrg CVS
         Component: DRM/Intel
           Product: DRI

Created attachment 83890
  --> https://bugs.freedesktop.org/attachment.cgi?id=83890&action=edit
dmesg from UX31A running under 3.10.5 with drm.debug=0xe

This has been reported in ALT Linux bugzilla (in Russian), posting here at
Kirill's request as I've confirmed a report by another user on the same
hardware I happen to use.

3.10.x kernels up to and including 3.10.5 result in turning off the backlight
at i915 module load time on ASUS UX31A (i7-3517U); dmesg with drm.debug=0xe and
late module load (not in initrd) is attached; external VGA monitor works fine
(dmesg and Xorg.1.log available if needed).

Here's a transcript of sysfs knob fiddling over ssh:

root at ux class/backlight/intel_backlight # cat actual_brightness 
0
root at ux class/backlight/intel_backlight # cat max_brightness 
4302
root at ux class/backlight/intel_backlight # echo 800 > brightness       
root at ux class/backlight/intel_backlight # cat actual_brightness       
4302

and corresponding bits of dmesg (including further attempts at putting 100 and
80 values into brightness; both resulted in actual_brightness reading the same
values but the screen backlight is still off):

[  877.052934] [drm:intel_panel_actually_set_backlight], set backlight PWM =
4302
[  881.868818] [drm:intel_panel_get_backlight], get backlight PWM = 4302
[  974.670199] [drm:intel_panel_get_backlight], get backlight PWM = 4302
[  978.469350] [drm:intel_panel_actually_set_backlight], set backlight PWM =
100
[  981.176898] [drm:intel_panel_get_backlight], get backlight PWM = 100
[  990.186065] [drm:intel_panel_actually_set_backlight], set backlight PWM = 80

acpi_video0 doesn't have any effect either.

This bug hasn't manifested itself on 3.9.7 with very similar configuration on
the same hardware.

I've skimmed over bug #51394 and bug #66462 which might be related; #54687 and
#65652 seem rather not.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20130809/760052ba/attachment.html>