drm: support for rotated scanout

For drivers that can support rotated scanout, the extra parameter
checking in drm-core, while nice, tends to get confused.  To solve
this drivers can set the crtc or plane invert_dimensions field so
that the dimension checking takes into account the rotation that
the driver is performing.

v1: original
v2: remove invert_dimensions from plane, at Ville's suggestion.
    Userspace can give rotated src coordinates, so invert_dimensions
    is not required for planes.

Signed-off-by: Rob Clark <rob@ti.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

include/drm/drm_crtc.h

@@ -368,6 +368,9 @@ struct drm_crtc_funcs {
  * @enabled: is this CRTC enabled?
  * @mode: current mode timings
  * @hwmode: mode timings as programmed to hw regs
+ * @invert_dimensions: for purposes of error checking crtc vs fb sizes,
+ *    invert the width/height of the crtc.  This is used if the driver
+ *    is performing 90 or 270 degree rotated scanout
  * @x: x position on screen
  * @y: y position on screen
  * @funcs: CRTC control functions
@@ -401,6 +404,8 @@ struct drm_crtc {
 	 */
 	struct drm_display_mode hwmode;
 
+	bool invert_dimensions;
+
 	int x, y;
 	const struct drm_crtc_funcs *funcs;