[Intel-gfx] [PATCH] drm/i915/fbc: only update no_fbc_reason when active

[Daniel Vetter]

On Fri, Aug 11, 2017 at 11:36:15AM +0100, Chris Wilson wrote:
> Quoting Daniel Vetter (2017-08-11 09:04:18)
> > On Fri, Aug 11, 2017 at 09:23:27AM +0200, Daniel Vetter wrote:
> > > In our snb farm in CI we have plenty of underruns, but not enough
> > > stolen memory to enable fbc. Which means every time there's an
> > > underrun the no_fbc_reason swichtes to something that makes
> > > kms_frontbuffer_tracking fail instead of skip, adding massive amounts
> > > of additional noise to igt test runs.
> > > 
> > > Make sure we don't try to disable fbc when it's off already.
> > > 
> > > Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> > > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > 
> > Note this seems to be the real bug that's causing all the spurious noise
> > on snb CI in the full run. So pretty important to land this fast.
> 
> Yup, this is more than just silencing CI, this looks to be a
> precondition for intel_fbc_deactivate() -- all other callers check for
> fbc->enabled before calling deactivate. I would even suggest we add a
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index 122d6372f58d..0c6e66f8a0f1 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -485,6 +485,9 @@ static void intel_fbc_deactivate(struct drm_i915_private *dev_priv)
>  
>         WARN_ON(!mutex_is_locked(&fbc->lock));
>  
> +       if (WARN_ON(!fbc->enabled))
> +               return;
> +

Good idea, squashed in and applied.
-Daniel

> 
> Either way,
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> -Chris

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch