Re: [PATCH] drm/i915: Fix SKL+ 90/270 degree rotated plane coordinate computation

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

On Tue, Oct 25, 2016 at 08:20:46AM +0100, Chris Wilson wrote:
> On Mon, Oct 24, 2016 at 07:13:04PM +0300, ville.syrjala@linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Pass the framebuffer size in .16 fixed point coordinates to
> > drm_rect_rotate() since that's what the source coordinates are as well
> > at this stage. We used to do this part of the computation in integer
> > coordinates, but that got changed when moving the computation to
> > happen in the check phase of the operation. Unfortunately I forgot
> > to shift up the fb width and height appropriately.
> > 
> > With the bogus size we ended up with some negative fb offset, which when
> > added to the vma offset caused out scanout to start at an offset earlier
> > than we inteded. Eg. when testing on my SKL I saw a row of incorrect
> > tiles at the top of my screen.
> > 
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> > Cc: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
> > Cc: drm-intel-fixes@lists.freedesktop.org
> > Fixes: b63a16f6cd89 ("drm/i915: Compute display surface offset in the plane check hook for SKL+")
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 5a036999487b..c783f884f85d 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -2985,7 +2985,8 @@ int skl_check_plane_surface(struct intel_plane_state *plane_state)
> >  	/* Rotate src coordinates to match rotated GTT view */
> >  	if (drm_rotation_90_or_270(rotation))
> >  		drm_rect_rotate(&plane_state->base.src,
> > -				fb->width, fb->height, DRM_ROTATE_270);
> > +				fb->width << 16, fb->height << 16,
> > +				DRM_ROTATE_270);
> 
> Line 2576 (intel_fill_fb_info()) also looks wrong.
> 
> drm_rect_rotate(&r,
> 		rot_info->plane[i].width * tile_width,
> 		rot_info->plane[i].height * tile_height,
> 		DRM_ROTATE_270);

That should be fine. No sub-pixel stuff going on in that
function.

-- 
Ville Syrjälä
Intel OTC
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