drm/i915: Don't reject primary plane windowing with color keying enabled on SKL+

BugLink: http://bugs.launchpad.net/bugs/1553179

commit 6f94b6dd upstream.

On SKL+ plane scaling is mutually exclusive with color keying. The code
check for this, but during some refactoring the code got changed to
also reject primary plane windowing when color keying is used. There is
no such restriction in the hardware, so restore the original logic.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Fixes: 061e4b8d ("drm/i915: clean up atomic plane check functions, v2.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452883613-28549-1-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
(cherry picked from commit 693bdc28)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/gpu/drm/i915/intel_display.c

@@ -13545,11 +13545,12 @@ intel_check_primary_plane(struct drm_plane *plane,
 	int max_scale = DRM_PLANE_HELPER_NO_SCALING;
 	bool can_position = false;
 
-	/* use scaler when colorkey is not required */
-	if (INTEL_INFO(plane->dev)->gen >= 9 &&
-	    state->ckey.flags == I915_SET_COLORKEY_NONE) {
-		min_scale = 1;
-		max_scale = skl_max_scale(to_intel_crtc(crtc), crtc_state);
+	if (INTEL_INFO(plane->dev)->gen >= 9) {
+		/* use scaler when colorkey is not required */
+		if (state->ckey.flags == I915_SET_COLORKEY_NONE) {
+			min_scale = 1;
+			max_scale = skl_max_scale(to_intel_crtc(crtc), crtc_state);
+		}
 		can_position = true;
 	}