[Intel-gfx] xrandr crashes X with a "GPU hung" in the i915 driver

[Chris Wilson]

On Fri, 5 Nov 2010 11:51:36 -0700, Bryan Freed <bfreed at chromium.org> wrote:
> Ah.  I see 9f54107f866a25cf670f81f7c52b8c108728c6a5 in git://
> anongit.freedesktop.org/xorg/driver/xf86-video-intel, but that change looks
> i830-specific.  We are running i915.
> 
> My i915_error_state looks like this in a few test runs this morning:
> 
> localhost ~ # cd /sys/kernel/debug/dri/0/
> localhost 0 # cat i915_error_state
> Time: 1288979468 s 955942 us
> EIR: 0x00000000
>   PGTBL_ER: 0x00000000
>   INSTPM: 0x00000000
>   IPEIR: 0x00000000
>   IPEHR: 0x01800002
>   INSTDONE: 0x7dffffc1
>   ACTHD: 0x07357014

That's an old kernel, not a lot of information in the i915_error_state.
0x01800002 is MI_WAIT_FOR_EVENT. The issue is that we are doing a
mode switch whilst there is a pending WAIT, so by the time the GPU
executes the wait the pipe is disabled and the GPU hangs. I just this
morning committed a patch to -intel that might help here.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre