[Bug 29255] New: DisplayPort output distorted

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=29255

           Summary: DisplayPort output distorted
           Product: xorg
           Version: 7.5
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: major
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: mail at andreas-demmer.de
         QAContact: xorg-team at lists.x.org


Created an attachment (id=37394)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=37394)
distortions on external display

I have a notebook with switchable graphics (discrete ATI Mobility Radeon HD 
5650 and integrated Intel Arrandale). The DisplayPort only works with the 
discrete adapter but this limitation also exists in Windows, so I guess the 
DisplayPort is hard-wired to the discrete card.

If I use the radeon driver, it detects whenever I plug something into the 
DisplayPort. E.g. I have a DisplayPort-to-VGA adapter (for projectors) and 
test it with my LCD monitor that luckily has a VGA input, too. xrandr detects 
the connection and suggests the correct resolution and frequency (1680x1050 
@60Hz). But the image is totally distorted. It looks like a old tube monitor 
that runs a too high frequency, you can see this on the attached screenshot.
What you cannot see, is that the distortions move quite fast and are not
static.

I switched back to 1024x768 at 60Hz but the problem persists and the optional
75.1Hz do not make any difference, too.

The same settings work fine with Windows, so I suspect this issue to be caused
by the radeon driver.

Is there any way to see what's going wrong and maybe fix this?

- Kernel 2.6.34
- XOrg 7.5
- xf86-driver-ati  6.13.0

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