[PATCH v3 4/4] drm/i915: Implement proper clipping for video sprites

[Ville Syrjälä]

On Tue, Apr 16, 2013 at 02:37:24PM +0100, Chris Wilson wrote:
> On Tue, Apr 16, 2013 at 01:47:22PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Properly clip the source when the destination gets clipped
> > by the pipe dimensions.
> > 
> > Sadly the video sprite hardware is rather limited so it can't do proper
> > sub-pixel postitioning. Resort to truncating the source coordinates to
> > (macro)pixel boundary.
> > 
> > The scaling checks are done using the relaxed drm_region functions.
> > That means that the src/dst regions are reduced in size in order to keep
> > the scaling factor within the limits.
> > 
> > Also do some additional checking against various hardware limits.
> > 
> > v2: Truncate src coords instead of rounding to avoid increasing src
> >     viewport size, and adapt to changes in drm_calc_{h,v}scale().
> > v3: Adapt to drm_region->drm_rect rename. Fix misaligned crtc_w for
> >     packed YUV formats when scaling isn't supported.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Skipping to the end, use of drm_rect looks good.
> 
> The one ugly that stood out is:
> 
> >  	/*
> >  	 * If the sprite is completely covering the primary plane,
> >  	 * we can disable the primary and save power.
> >  	 */
> > -	if ((crtc_x == 0) && (crtc_y == 0) &&
> > +	if (visible &&
> > +	    (crtc_x == 0) && (crtc_y == 0) &&
> >  	    (crtc_w == primary_w) && (crtc_h == primary_h))
> >  		disable_primary = true;
> 
> which would be
>   disable_primary = drm_rect_equals(&dst, &clip);
>   BUG_ON(disable_primary && !visible);
> with a little bit of massaging of crtc/dst.

Yeah, looks nicer. I'll add drm_rect_equals() to our repertoire.

-- 
Ville Syrjälä
Intel OTC