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

From: Chris Wilson
Date: Fri Oct 28 2011 - 08:56:48 EST

On Fri, 28 Oct 2011 20:22:35 +0800, Yong Zhang <yong.zhang0@xxxxxxxxx> 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
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 Wilson, Intel Open Source Technology Centre
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