[Intel-gfx] [PATCH 1/5] drm/i915: Fix scaling check for 90/270 degree plane rotation

[Chris Wilson]

On Mon, Nov 07, 2016 at 10:20:53PM +0200, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Starting from commit b63a16f6cd89 ("drm/i915: Compute display surface
> offset in the plane check hook for SKL+") we've already rotated the src
> coordinates by 270 degrees by the time we check if a scaler is needed
> or not, so we must not account for the rotation a second time.
> Previously we did these steps in the opposite order and hence the
> scaler check had to deal with rotation itself. The double rotation
> handling causes us to enable a scaler pretty much every time 90/270
> degree plane rotation is requested, leading to fuzzier fonts and whatnot.
> 
> Cc: Sivakumar Thulasimani <sivakumar.thulasimani at intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: drm-intel-fixes at lists.freedesktop.org
> Reported-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Fixes: b63a16f6cd89 ("drm/i915: Compute display surface offset in the plane check hook for SKL+")
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

I believe

	Tested-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

skl_plane_downscale_amount() ?
skl_plane_relative_data_rate() ?
skl_ddb_min_alloc()
skl_compute_plane_wm()

What's the best way of keeping the reader aware of whether or not the
coordinate transform has been applied? Similar to how to let the user
know the rect is in fixed_16_16 or int32.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre