Re: [PATCH 2/2] drm/i915: Reorder media/render reset on g4x

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, May 16, 2017 at 04:38:01PM +0300, Mika Kuoppala wrote:
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> 
> > Ville found a reference to WaMediaResetBeforeFullReset which we presume
> > means that we should simply do the media reset first.
> 
> Yesterday I reordered the resets but I recall it didnt help.
> I will retry but regardless yeah resetting media first makes
> sense.
> 
> >
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=100942
> > Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_uncore.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> > index fc3da0a6fdbb..c3d0d81b50e4 100644
> > --- a/drivers/gpu/drm/i915/intel_uncore.c
> > +++ b/drivers/gpu/drm/i915/intel_uncore.c
> > @@ -1504,12 +1504,6 @@ static int g4x_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> >  	struct pci_dev *pdev = dev_priv->drm.pdev;
> >  	int ret;
> >  
> > -	pci_write_config_byte(pdev, I915_GDRST,
> > -			      GRDOM_RENDER | GRDOM_RESET_ENABLE);
> > -	ret =  wait_for(g4x_reset_complete(pdev), 500);
> > -	if (ret)
> > -		goto out;
> > -
> >  	/* WaVcpClkGateDisableForMediaReset:ctg,elk */
> >  	I915_WRITE(VDECCLK_GATE_D, I915_READ(VDECCLK_GATE_D) | VCP_UNIT_CLOCK_GATE_DISABLE);
> >  	POSTING_READ(VDECCLK_GATE_D);
> > @@ -1517,11 +1511,17 @@ static int g4x_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> >  	pci_write_config_byte(pdev, I915_GDRST,
> >  			      GRDOM_MEDIA | GRDOM_RESET_ENABLE);
> >  	ret =  wait_for(g4x_reset_complete(pdev), 500);
> > +	if (ret)
> > +		goto out;
> >
> 
> We should restore the WaVcp... state if we fail. Not that it
> was right to begin with.

I had it that way so that one could figure out which part of the reset
failed by examining the registers afterwards. If we change that then
we should add more debug/error prints to let us know exactly what failed.

> 
> -Mika
> 
> >  	/* WaVcpClkGateDisableForMediaReset:ctg,elk */
> >  	I915_WRITE(VDECCLK_GATE_D, I915_READ(VDECCLK_GATE_D) & ~VCP_UNIT_CLOCK_GATE_DISABLE);
> >  	POSTING_READ(VDECCLK_GATE_D);
> >  
> > +	pci_write_config_byte(pdev, I915_GDRST,
> > +			      GRDOM_RENDER | GRDOM_RESET_ENABLE);
> > +	ret =  wait_for(g4x_reset_complete(pdev), 500);
> > +
> >  out:
> >  	pci_write_config_byte(pdev, I915_GDRST, 0);
> >  	return ret;
> > -- 
> > 2.11.0

-- 
Ville Syrjälä
Intel OTC
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