drm/i915: Fix SKL+ watermarks for 90/270 rotation

skl_check_plane_surface() already rotates the clipped plane source
coordinates to match the scanout direction because that's the way
the GTT mapping is set up. Thus we no longer need to rotate the
coordinates in the watermark code.

For cursors we use the non-clipped coordinates which are not rotated
appropriately, but that doesn't actually matter since cursors don't
even support 90/270 degree rotation.

v2: Resolve conflicts from SKL+ wm rework

Cc: stable@vger.kernel.org
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: b63a16f6 ("drm/i915: Compute display surface offset in the plane check hook for SKL+")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170331180056.14086-3-ville.syrjala@linux.intel.comTested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -3841,20 +3841,26 @@ skl_plane_downscale_amount(const struct intel_crtc_state *cstate,
 
 	/* n.b., src is 16.16 fixed point, dst is whole integer */
 	if (plane->id == PLANE_CURSOR) {
+		/*
+		 * Cursors only support 0/180 degree rotation,
+		 * hence no need to account for rotation here.
+		 */
 		src_w = pstate->base.src_w >> 16;
 		src_h = pstate->base.src_h >> 16;
 		dst_w = pstate->base.crtc_w;
 		dst_h = pstate->base.crtc_h;
 	} else {
+		/*
+		 * Src coordinates are already rotated by 270 degrees for
+		 * the 90/270 degree plane rotation cases (to match the
+		 * GTT mapping), hence no need to account for rotation here.
+		 */
 		src_w = drm_rect_width(&pstate->base.src) >> 16;
 		src_h = drm_rect_height(&pstate->base.src) >> 16;
 		dst_w = drm_rect_width(&pstate->base.dst);
 		dst_h = drm_rect_height(&pstate->base.dst);
 	}
 
-	if (drm_rotation_90_or_270(pstate->base.rotation))
-		swap(dst_w, dst_h);
-
 	fp_w_ratio = fixed_16_16_div(src_w, dst_w);
 	fp_h_ratio = fixed_16_16_div(src_h, dst_h);
 	downscale_w = max_fixed_16_16(fp_w_ratio, u32_to_fixed_16_16(1));
@@ -3978,12 +3984,14 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
 	if (y && format != DRM_FORMAT_NV12)
 		return 0;
 
+	/*
+	 * Src coordinates are already rotated by 270 degrees for
+	 * the 90/270 degree plane rotation cases (to match the
+	 * GTT mapping), hence no need to account for rotation here.
+	 */
 	width = drm_rect_width(&intel_pstate->base.src) >> 16;
 	height = drm_rect_height(&intel_pstate->base.src) >> 16;
 
-	if (drm_rotation_90_or_270(pstate->rotation))
-		swap(width, height);
-
 	/* for planar format */
 	if (format == DRM_FORMAT_NV12) {
 		if (y)  /* y-plane data rate */
@@ -4066,12 +4074,14 @@ skl_ddb_min_alloc(const struct drm_plane_state *pstate,
 	    fb->modifier != I915_FORMAT_MOD_Yf_TILED)
 		return 8;
 
+	/*
+	 * Src coordinates are already rotated by 270 degrees for
+	 * the 90/270 degree plane rotation cases (to match the
+	 * GTT mapping), hence no need to account for rotation here.
+	 */
 	src_w = drm_rect_width(&intel_pstate->base.src) >> 16;
 	src_h = drm_rect_height(&intel_pstate->base.src) >> 16;
 
-	if (drm_rotation_90_or_270(pstate->rotation))
-		swap(src_w, src_h);
-
 	/* Halve UV plane width and height for NV12 */
 	if (fb->format->format == DRM_FORMAT_NV12 && !y) {
 		src_w /= 2;
@@ -4460,13 +4470,15 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 		width = intel_pstate->base.crtc_w;
 		height = intel_pstate->base.crtc_h;
 	} else {
+		/*
+		 * Src coordinates are already rotated by 270 degrees for
+		 * the 90/270 degree plane rotation cases (to match the
+		 * GTT mapping), hence no need to account for rotation here.
+		 */
 		width = drm_rect_width(&intel_pstate->base.src) >> 16;
 		height = drm_rect_height(&intel_pstate->base.src) >> 16;
 	}
 
-	if (drm_rotation_90_or_270(pstate->rotation))
-		swap(width, height);
-
 	cpp = fb->format->cpp[0];
 	plane_pixel_rate = skl_adjusted_plane_pixel_rate(cstate, intel_pstate);