[Known BUG?] i915 hang on 3.0.0-12 (Ubuntu 11.10 release)

[Chris Wilson]

On Fri, 28 Oct 2011 20:22:35 +0800, Yong Zhang <yong.zhang0 at gmail.com> wrote:
> Hi,
> 
> Just got below error on Ubuntu-11.10 (kernel: 3.0.0-12-generic),
> and after that my screen can't show normally.
> No sure if it's a known issue.

No, that is the first time I've seen that. It looks as if the fence was
not released, or reacquired, before the the batch was executed. (There
is a later batch that also uses this buffer.)

The fence is programmed with:
  fence[15] = 04e00001
    valid, x-tiled, pitch: 512, start: 0x04e00000, size: 1048576

And the BLT command uses:
  0x0df006b0:      0x54300004: XY_COLOR_BLT (rgb enabled, alpha enabled, dst tile 
0)
  0x0df006b4:      0x03f00100:    format 8888, pitch 256, clipping disabled
  0x0df006b8:      0x00000000:    (0,0)
  0x0df006bc:      0x00140037:    (55,20)
  0x0df006c0:      0x04e00000:    offset 0x04e00000
  0x0df006c4:      0x00000000:    color
  0x0df006c8:      0x54f00006: XY_SRC_COPY_BLT (rgb enabled, alpha enabled, src tile 0, dst tile 0)
  0x0df006cc:      0x03cc0100:    format 8888, dst pitch 256, clipping disabled
  0x0df006d0:      0x00000000:    dst (0,0)
  0x0df006d4:      0x00140037:    dst (55,20)
  0x0df006d8:      0x04e00000:    dst offset 0x04e00000
  0x0df006dc:      0x012c0003:    src (3,300)
  0x0df006e0:      0x00000400:    src pitch 1024
  0x0df006e4:      0x08500000:    src offset 0x08500000

So we try to perform an undefined operation and the GPU hangs. I suspect
this will be timing dependent, but if you can find a way to reproduce
it, that would be very useful.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre