[Bug 44800] Radeon HD 6450 CAICOS screen corruption and kernel crashes

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=44800

--- Comment #9 from Marko Kohtala <marko.kohtala at gmail.com> 2012-01-16 11:43:20 PST ---
Created attachment 55651
  --> https://bugs.freedesktop.org/attachment.cgi?id=55651
Artefacts in X, screencapture

This capture was with the enable_mtrr_cleanup mtrr_spare_reg_nr=1 to kernel.
Here I started the X server from command line and only an xterm and a window
manager. 

The artefacts appear to the window while I scroll the window pressing enter.

There was some constantly running horizontal artefacts, but they were
flickering and got erased immediately thus leaving no mark. Seems like it could
be ramdac reading bad for some scanlines, but more likely it goes on in the
framebuffer. The blue part lower in the window could be one of those caught. I
wonder if the squares in the xterm window are a result of that flickering, but
due to scrolling it does not get erased.

The blue and green spots came one by one slowly while doing something else in
the xterm. They stayed.

This happens only with this CAICOS card (I have an older radeon X300 that has
no problems, as well as a nVidia card goes without these problems). So I'd
expect whatever memory corruption there is, it is somehow in the CAICOS support
in kernel.

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