[Bug 79581] New: [Regression] Internal backlight brightness initially set to 0 when external display is connected

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=79581

          Priority: medium
            Bug ID: 79581
          Assignee: chris at chris-wilson.co.uk
           Summary: [Regression] Internal backlight brightness initially
                    set to 0 when external display is connected
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: major
    Classification: Unclassified
                OS: Linux (All)
          Reporter: michael.monreal+bugs at gmail.com
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: 6.7.0
         Component: Driver/intel
           Product: xorg

When I boot my laptop with "Intel(R) HD Graphics 4000" and my external display
connected via Mini DisplayPort (only connector), the brightness
(/sys/class/backlight/intel_backlight/brightness) of the internal screen is set
to 0 each time the X server is started:

a) After boot, GDM starts and the internal screen turns black. I can still log
in blindly. I can also go to a VT and back (ctrl-alt-f2, alt-f1) and the
brightness will be fine.

b) When GNOME starts (new X server I suppose?) the same thing happens again.
Going to a VT and back does NOT work around the problem, I need to do something
like "echo 4000 > /sys/class/backlight/intel_backlight/brightness" or try to
navigate to the brightness control manually.

This is on Fedora 20 with the following packages:
- xorg-x11-drv-intel-2.21.15-5.fc20.x86_64
- kernel-3.14.4-200.fc20.x86_64

I can also reproduce this 100% on the Fedora 20 live CD, which has:
- xorg-x11-drv-intel-2.21.15-5.fc20.x86_64
- kernel-3.11.10-301.fc20.x86_64

This is a regression from Fedora 19, where it used to work fine. I just
verified again and the problem does not show onf the Fedora 19 live CD, which
has:
- xorg-x11-drv-intel-2.21.8-1.fc19.x86_64
- kernel-3.9.5-301.fc19.x86_64

If there is anything else I can provide please ask me.

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