drm/i915: Deprecate I915_SET_COLORKEY_NONE

Deprecate the silly I915_SET_COLORKEY_NONE flag. The obvious
way to disable colorkey is to just set flags to 0, which is
exactly what the intel ddx has been doing all along.

Currently when userspace sets the flags to 0, we end up in a
funny state where colorkey is disabled, but various colorkey
vs. scaling checks still consider colorkey to be enabled, and
thus we don't allow plane scaling to kick in.

In case there is some other userspace out there that actually
uses this flag (unlikely as this is an i915 specific uapi)
we'll keep on accepting it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180202204231.27905-1-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_atomic_plane.c

@@ -56,7 +56,6 @@ intel_create_plane_state(struct drm_plane *plane)
 
 	state->base.plane = plane;
 	state->base.rotation = DRM_MODE_ROTATE_0;
-	state->ckey.flags = I915_SET_COLORKEY_NONE;
 
 	return state;
 }

drivers/gpu/drm/i915/intel_display.c

@@ -4787,7 +4787,7 @@ static int skl_update_scaler_plane(struct intel_crtc_state *crtc_state,
 		return ret;
 
 	/* check colorkey */
-	if (plane_state->ckey.flags != I915_SET_COLORKEY_NONE) {
+	if (plane_state->ckey.flags) {
 		DRM_DEBUG_KMS("[PLANE:%d:%s] scaling with color key not allowed",
 			      intel_plane->base.base.id,
 			      intel_plane->base.name);
@@ -12788,7 +12788,7 @@ intel_check_primary_plane(struct intel_plane *plane,
 
 	if (INTEL_GEN(dev_priv) >= 9) {
 		/* use scaler when colorkey is not required */
-		if (state->ckey.flags == I915_SET_COLORKEY_NONE) {
+		if (!state->ckey.flags) {
 			min_scale = 1;
 			max_scale = skl_max_scale(to_intel_crtc(crtc), crtc_state);
 		}

drivers/gpu/drm/i915/intel_sprite.c

@@ -894,7 +894,7 @@ intel_check_sprite_plane(struct intel_plane *plane,
 	/* setup can_scale, min_scale, max_scale */
 	if (INTEL_GEN(dev_priv) >= 9) {
 		/* use scaler when colorkey is not required */
-		if (state->ckey.flags == I915_SET_COLORKEY_NONE) {
+		if (!state->ckey.flags) {
 			can_scale = 1;
 			min_scale = 1;
 			max_scale = skl_max_scale(crtc, crtc_state);
@@ -1070,6 +1070,9 @@ int intel_sprite_set_colorkey(struct drm_device *dev, void *data,
 	struct drm_modeset_acquire_ctx ctx;
 	int ret = 0;
 
+	/* ignore the pointless "none" flag */
+	set->flags &= ~I915_SET_COLORKEY_NONE;
+
 	/* Make sure we don't try to enable both src & dest simultaneously */
 	if ((set->flags & (I915_SET_COLORKEY_DESTINATION | I915_SET_COLORKEY_SOURCE)) == (I915_SET_COLORKEY_DESTINATION | I915_SET_COLORKEY_SOURCE))
 		return -EINVAL;

include/uapi/drm/i915_drm.h

@@ -1358,7 +1358,9 @@ struct drm_intel_overlay_attrs {
  * active on a given plane.
  */
 
-#define I915_SET_COLORKEY_NONE		(1<<0) /* disable color key matching */
+#define I915_SET_COLORKEY_NONE		(1<<0) /* Deprecated. Instead set
+						* flags==0 to disable colorkeying.
+						*/
 #define I915_SET_COLORKEY_DESTINATION	(1<<1)
 #define I915_SET_COLORKEY_SOURCE	(1<<2)
 struct drm_intel_sprite_colorkey {