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

[Gore, Tim]

> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Gore, Tim
> Sent: Wednesday, June 03, 2015 9:43 AM
> To: Chris Wilson
> Cc: intel-gfx at lists.freedesktop.org; Wood, Thomas
> Subject: Re: [Intel-gfx] [PATCH i-g-t] tests/gem_reset_stats : mask off
> ring_stop bits
> 
> 
> 
> > -----Original Message-----
> > From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> > Sent: Wednesday, June 03, 2015 9:30 AM
> > To: Gore, Tim
> > Cc: intel-gfx at lists.freedesktop.org; Wood, Thomas
> > Subject: Re: [Intel-gfx] [PATCH i-g-t] tests/gem_reset_stats : mask
> > off ring_stop bits
> >
> > 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
> 
> Sounds good to me. I think most people here (Egham) see the stop rings
> interface as Being a rather nasty hack, and it certainly makes pain for the TDR
> mechanism.
> 
>   Tim

However it would still be good to get this fix in for now. I'll start looking
At removing the use of stop_rings from IGT when I've finished my current
Crop of HSD's, so if someone could push this patch it would be appreciated.
One less test failure to be reported :-)

   Tim
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