[Intel-gfx] [PATCH i-g-t] tests/gem_reset_stats : mask off ring_stop bits

[Chris Wilson]

On Wed, Jun 03, 2015 at 09:20:21AM +0100, tim.gore at intel.com wrote:
> From: Tim Gore <tim.gore at intel.com>
> 
> Function check_gpu_ok checks to make sure that any hangs
> have cleared by testing for (flags == 0). Some tests set
> the STOP_RINGS_ALLOW_BAN and STOP_RINGS_ALLOW_ERRORS flags
> but these do not get cleared by an individual ring reset,
> (a feature added recently to the driver), leading the
> check_gpu_ok function to think that the gpu is still hung.
> 
> So I mask the flags with STOP_RING_ALL, to ignore the mode
> bits and look only at the bits that stop the rings.
> 
> Once gpu_check_ok sees that the gpu is not hung I write 0
> to stop_rings in order to clear it completely. This is
> because igt_set_stop_rings will only write to stop_rings
> if either a) they are currently 0 or b) we are writing 0.
> If we leave the mode bits set then subsequent calls to
> igt_set_stop_rings to create hangs will fail.

Can we please just deprecate the stop_rings interface? We can do
explicit hang injection and GPU resets on gen4+, most of gen3 but not
gen2. Even if we mask of testing for gen2/3, that still provides
(almost, just a couple of gen2/3 reset functions will be missed) complete
coverage of GEM reset handling.

The benefit is we lose this attrocious interface and remove some hideous
complications from the kernel.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre