Re: [PATCH 1/4] drm/i915/fbc: update busy_bits even for GTT and flip flushes

["Zanoni, Paulo R" <paulo.r.zanoni@intel.com>]

Em Ter, 2016-03-22 às 12:13 +0100, Daniel Vetter escreveu:
> On Mon, Mar 21, 2016 at 04:26:54PM -0300, Paulo Zanoni wrote:
> > 
> > We ignore ORIGIN_GTT because the hardware tracking can recognize
> > GTT
> > writes and take care of them. We also ignore ORIGIN_FLIP because we
> > deal with flips without relying on the frontbuffer tracking
> > infrastructure. On the other hand, a flush is a flush and means
> > we're
> > good to go, so we need to update busy_bits in order to reflect
> > that,
> > even if we're not going to do anything else about it.
> > 
> > How to reproduce the bug fixed by this patch:
> >  - boot SKL up to the desktop environment
> >  - stop the display manager
> >  - run any of the igt/kms_frontbuffer_tracking/*fbc*onoff* subtests
> >  - the tests will fail
> > 
> > The steps above will create the right conditions for us to lose
> > track
> > of busy_bits. If you, for example, run the full set of FBC tests,
> > the
> > onoff subtests will succeed.
> > 
> > Also notice that the "bug" is that we'll just keep FBC disabled on
> > cases where it could be enabled, so it's not something the users
> > can
> > perceive, it just affects power consumption numbers on properly
> > configured machines.
> > 
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Is this covered by your nasty igt test suite? Kernel side looks good,
> so
> with appropriate Testcase: tag added:

I mentioned the tests in the middle of the commit message, but forgot
the Testcase tags. I'll add them.

> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Thanks!

> 
> > 
> > ---
> >  drivers/gpu/drm/i915/intel_fbc.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_fbc.c
> > b/drivers/gpu/drm/i915/intel_fbc.c
> > index 2e571f5..b8ba79c 100644
> > --- a/drivers/gpu/drm/i915/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/intel_fbc.c
> > @@ -996,13 +996,13 @@ void intel_fbc_flush(struct drm_i915_private
> > *dev_priv,
> >  	if (!fbc_supported(dev_priv))
> >  		return;
> >  
> > -	if (origin == ORIGIN_GTT || origin == ORIGIN_FLIP)
> > -		return;
> > -
> >  	mutex_lock(&fbc->lock);
> >  
> >  	fbc->busy_bits &= ~frontbuffer_bits;
> >  
> > +	if (origin == ORIGIN_GTT || origin == ORIGIN_FLIP)
> > +		goto out;
> > +
> >  	if (!fbc->busy_bits && fbc->enabled &&
> >  	    (frontbuffer_bits &
> > intel_fbc_get_frontbuffer_bit(fbc))) {
> >  		if (fbc->active)
> > @@ -1011,6 +1011,7 @@ void intel_fbc_flush(struct drm_i915_private
> > *dev_priv,
> >  			__intel_fbc_post_update(fbc->crtc);
> >  	}
> >  
> > +out:
> >  	mutex_unlock(&fbc->lock);
> >  }
> >  
> > -- 
> > 2.7.0
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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