drm/i915: Add horizontal mirroring support for CHV pipe B planes

The primary and sprite planes on CHV pipe B support horizontal
mirroring. Expose it to the world.

Sadly the hardware ignores the mirror bit when the rotate bit is
set, so we'll have to reject the 180+X case.

v2: Drop the BIT()
v3: Pass dev_priv instead of dev to IS_CHERRYVIEW()

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1479142440-25283-4-git-send-email-ville.syrjala@linux.intel.com
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ecc7b5b..c2ba36b 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3078,6 +3078,9 @@ static void i9xx_update_primary_plane(struct drm_plane *primary,
 	if (rotation & DRM_ROTATE_180)
 		dspcntr |= DISPPLANE_ROTATE_180;
 
+	if (rotation & DRM_REFLECT_X)
+		dspcntr |= DISPPLANE_MIRROR;
+
 	if (IS_G4X(dev_priv))
 		dspcntr |= DISPPLANE_TRICKLE_FEED_DISABLE;
 
@@ -3090,6 +3093,8 @@ static void i9xx_update_primary_plane(struct drm_plane *primary,
 	if (rotation & DRM_ROTATE_180) {
 		x += crtc_state->pipe_src_w - 1;
 		y += crtc_state->pipe_src_h - 1;
+	} else if (rotation & DRM_REFLECT_X) {
+		x += crtc_state->pipe_src_w - 1;
 	}
 
 	linear_offset = intel_fb_xy_to_linear(x, y, plane_state, 0);
@@ -15065,6 +15070,10 @@ intel_primary_plane_create(struct drm_i915_private *dev_priv, enum pipe pipe)
 		supported_rotations =
 			DRM_ROTATE_0 | DRM_ROTATE_90 |
 			DRM_ROTATE_180 | DRM_ROTATE_270;
+	} else if (IS_CHERRYVIEW(dev_priv) && pipe == PIPE_B) {
+		supported_rotations =
+			DRM_ROTATE_0 | DRM_ROTATE_180 |
+			DRM_REFLECT_X;
 	} else if (INTEL_GEN(dev_priv) >= 4) {
 		supported_rotations =
 			DRM_ROTATE_0 | DRM_ROTATE_180;