Re: [Intel-gfx] [PATCH 2/2] drm/i915/dgfx: Do not write in removed FBC fence registers

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

On Tue, Feb 04, 2020 at 02:06:23AM +0000, Souza, Jose wrote:
> On Wed, 2020-01-29 at 13:42 +0200, Ville Syrjälä wrote:
> > On Tue, Jan 28, 2020 at 03:52:41PM -0800, José Roberto de Souza
> > wrote:
> > > From: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
> > > 
> > > dgfx platforms do not support CPU fence and FBC host tracking so
> > > lets avoid write to removed registers.
> > > 
> > > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > > Cc: Matt Roper <matthew.d.roper@intel.com>
> > > Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> > > Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com
> > > >
> > > Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_fbc.c | 7 ++++++-
> > >  1 file changed, 6 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c
> > > b/drivers/gpu/drm/i915/display/intel_fbc.c
> > > index 1f0d24a1dec1..12900b8ce28e 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > > @@ -314,7 +314,12 @@ static void gen7_fbc_activate(struct
> > > drm_i915_private *dev_priv)
> > >  		break;
> > >  	}
> > >  
> > > -	if (params->fence_id >= 0) {
> > > +	if (IS_DGFX(dev_priv)) {
> > > +		/*
> > > +		 * dGFX GPUs don't have apperture or fences and only
> > > rely on FBC
> > > +		 * render nuke to track frontbuffer modifications
> > > +		 */
> > > +	} else if (params->fence_id >= 0) {
> > >  		dpfc_ctl |= IVB_DPFC_CTL_FENCE_EN;
> > >  		intel_de_write(dev_priv, SNB_DPFC_CTL_SA,
> > >  			       SNB_CPU_FENCE_ENABLE | params-
> > > >fence_id);
> > 
> > if (fence) {
> > 	do stuff
> > } else if (num_fences) {
> > 	do other stuff
> > }
> 
> Did not get what you want here.

Don't add a silly looking empty if block.

And don't make the assumption that dgfx is the only thing that
has no fences, instead actually check if we have fences or not.

> It is covering all cases:
> - DGFX that don't have the registers
> - Setting the registers when fence_id >= 0
> - Clearing the register when fences_id == -1
> 
> > 
> > > -- 
> > > 2.25.0
> > > 
> > > _______________________________________________
> > > Intel-gfx mailing list
> > > Intel-gfx@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel
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