/* 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;
                src_h = pstate->base.src_h;
                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);
                src_h = drm_rect_height(&pstate->base.src);
                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);
-
        downscale_h = max(src_h / dst_h, (uint32_t)DRM_PLANE_HELPER_NO_SCALING);
        downscale_w = max(src_w / dst_w, (uint32_t)DRM_PLANE_HELPER_NO_SCALING);
 
        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 */
            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;
                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);