[Intel-gfx] [PATCH 1/7] drm/i915: Avoid the gpu reset vs. modeset deadlock

[Chris Wilson]

Quoting Daniel Vetter (2017-07-20 21:04:50)
> On Thu, Jul 20, 2017 at 9:47 PM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> >> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >> index 02b1f4966049..995522e40ec1 100644
> >> --- a/drivers/gpu/drm/i915/intel_display.c
> >> +++ b/drivers/gpu/drm/i915/intel_display.c
> >> @@ -3471,6 +3471,12 @@ void intel_prepare_reset(struct drm_i915_private *dev_priv)
> >>             !gpu_reset_clobbers_display(dev_priv))
> >>                 return;
> >>
> >> +       /* We have a modeset vs reset deadlock, defensively unbreak it.
> >> +        *
> >> +        * FIXME: We can do a _lot_ better, this is just a first iteration.*/
> >> +       i915_gem_set_wedged(dev_priv);
> >> +       DRM_DEBUG_DRIVER("Wedging GPU to avoid deadlocks with pending modeset updates\n");
> >
> > I meant this a dev_err(). It has user visible impact and user data loss.
> 
> stop_rings is gone so I can't differentiate, and DRM_ERROR breaks CI.
> Which after your timeout is the only point of this patch really.

So drop this patch. If the only reason is to sweep the bug under the
carpet, don't. I thought this patch was to move the wedge to where you
planned to replace it with the refined approach to abort the modeset.	

> guess I could throw a pr_notice or so in there, but we already do
> that. This was all removed in
> 
> commit 7b4d3a16dd97be0ebc793ea046b9af9d5c9b1b1a
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Mon Jul 4 08:08:37 2016 +0100
> 
>     drm/i915: Remove stop-rings debugfs interface
> 
> Should I explain this better in the commit message? I tried already ...

No idea what you mean. If you mean you want to know whether this error
was simulated or not, look in the error state. But the point of this
series is to avoid the dev_err() in the first place, in which case why
do we care whether it was simulated or not, if we hit the err it is a
bug and CI should be flagging it.
-Chris