[Bug 72289] New: [GM45] LCD waterfall effect on HP 2230s laptop

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=72289

          Priority: medium
            Bug ID: 72289
          Assignee: chris at chris-wilson.co.uk
           Summary: [GM45] LCD waterfall effect on HP 2230s laptop
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: Linux (All)
          Reporter: jza at saunalahti.fi
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: 7.7 (2011)
         Component: Driver/intel
           Product: xorg

System environment:
-- chipset: GM45
-- system architecture: x86_64
-- xserver-xorg-video-intel: 2:2.99.904-0ubuntu2
-- xserver-xorg: 1:7.7+1ubuntu6
-- kernel: 3.11.0-12-generic
-- Linux distribution: Xubuntu 13.10
-- Machine or mobo model: Hewlett-Packard 2230s (FU312EA#AK8), BIOS: 68PHU Ver.
F20
-- Display connector: LVDS

Reproducing steps: Reproducable always by using the X.org desktop normally.

Additional info:

The display of the laptop has a waterfall interference effect when used with
the Linux Intel GPU driver. The effect is more pronounced the lower the display
brightness is set. On maximum brightness, the effect cannot be perceived.

The screen is completely calm on all brightness levels when the Windows driver
is used. Notice though that the bad effect is also present in BIOS menus and
when an operating system with a generic display driver is used. Maybe the
driver or LCD panel has to be configured in certain way to make the effect
disappear.

I captured a short video showing the effect:
http://users.metropolia.fi/~joonasms/waterfall.3gp

In the included dmesg with drm.debug=0x06 I have booted the machine with
maximum brightness, then adjusted it all the way down, and then back all the
way up.

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