915gm/945gm/XAA lockup playing Xv video a second time (after mode-switch)

Peter Clifton pcjc2 at cam.ac.uk
Fri Oct 12 12:18:08 PDT 2007

There is another bug I've hit with the intel driver, where playing Xv
video at first works, then after a mode-switch (say to VT1 and back),
attempting to play Xv will result in a blue overlay and some seconds
afterwards, a GPU lockup.

The following seems to fix it for me by forcing a reset of the Xv regs
after a mode-switch (Does the reset to VT1 clears them?), however I'm
not sure whether it is a "fix" or a "workaround":

--- xserver-xorg-video-intel-2.1.1.bwh.pcjc2.orig/src/i830_video.c      2007-10-11 17:31:01.000000000 +0100
+++ xserver-xorg-video-intel-2.1.1.bwh.pcjc2/src/i830_video.c   2007-10-11 17:31:01.000000000 +0100
@@ -2927,6 +2927,7 @@
        I830StopVideo(pScrn, pPriv, TRUE);
        pPriv->overlayOK = FALSE;
+       pPriv->current_crtc = NULL;
        pPriv->oneLineMode = FALSE;

NB: This is on Ubuntu, which has a patch to force the Xv to use the
hardware overlay for XV. If that patch isn't present, I get a BadAlloc
when the driver tries textured video.

(I have a 1400x1050 display.. on a 945GM is that too big for textured


Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,

Tel: +44 (0)7729 980173 - (No signal in the lab!)

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