Bug#359328: Change screen resolution disables DRI

[Waldo Cancino <wcancino@icmc.usp.br>]

Hi again...

I try to use some openGL applications in my intel 915gm that uses dri at
 lower resolutions (ex. 1024x768, 800x600). I installed the mesa-experimental
 packages, and I have an update kernel 2.6.17. When I changed my resolution
 from 1280x800 to a lower resolution, dri stops working.

export LIBGL_DEBUG=verbose; glxgears

output
----------

libGL: XF86DRIGetClientDriverName: 1.6.0 i915 (screen 0)
libGL: OpenDriver: trying /usr/lib/dri/i915_dri.so
drmOpenByBusid: Searching for BusID pci:0000:00:02.0
drmOpenDevice: node name is /dev/dri/card0
drmOpenDevice: open result is 4, (OK)
drmOpenByBusid: drmOpenMinor returns 4
drmOpenByBusid: drmGetBusid reports pci:0000:00:02.0
libGL error: drmMap of framebuffer failed (Invalid argument)
libGL error: reverting to (slow) indirect rendering

But, when I come back from the max resolution dri works again. Can anyone
reproduce this problem ?

Waldo

PD: This problem happens with both i810 from unstable and the new snapshot
 1.6

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