drm/i915: Nuke intel_atomic_legacy_gamma_set

We do set DRIVER_ATOMIC now.

Note that the comment is outdated, the property paths switched over to
checking drm_drv_uses_atomic_modeset() a while ago. Which means this
can't even break if we revert DRIVER_ATOMIC again.

v2: Add note that this is even safer (Maarten).
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170403083304.9083-9-daniel.vetter@ffwll.ch

drivers/gpu/drm/i915/intel_display.c

@@ -13098,50 +13098,8 @@ void intel_crtc_restore_mode(struct drm_crtc *crtc)
 	drm_atomic_state_put(state);
 }
 
-/*
- * FIXME: Remove this once i915 is fully DRIVER_ATOMIC by calling
- *        drm_atomic_helper_legacy_gamma_set() directly.
- */
-static int intel_atomic_legacy_gamma_set(struct drm_crtc *crtc,
-					 u16 *red, u16 *green, u16 *blue,
-					 uint32_t size)
-{
-	struct drm_device *dev = crtc->dev;
-	struct drm_mode_config *config = &dev->mode_config;
-	struct drm_crtc_state *state;
-	int ret;
-
-	ret = drm_atomic_helper_legacy_gamma_set(crtc, red, green, blue, size);
-	if (ret)
-		return ret;
-
-	/*
-	 * Make sure we update the legacy properties so this works when
-	 * atomic is not enabled.
-	 */
-
-	state = crtc->state;
-
-	drm_object_property_set_value(&crtc->base,
-				      config->degamma_lut_property,
-				      (state->degamma_lut) ?
-				      state->degamma_lut->base.id : 0);
-
-	drm_object_property_set_value(&crtc->base,
-				      config->ctm_property,
-				      (state->ctm) ?
-				      state->ctm->base.id : 0);
-
-	drm_object_property_set_value(&crtc->base,
-				      config->gamma_lut_property,
-				      (state->gamma_lut) ?
-				      state->gamma_lut->base.id : 0);
-
-	return 0;
-}
-
 static const struct drm_crtc_funcs intel_crtc_funcs = {
-	.gamma_set = intel_atomic_legacy_gamma_set,
+	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.set_config = drm_atomic_helper_set_config,
 	.set_property = drm_atomic_helper_crtc_set_property,
 	.destroy = intel_crtc_destroy,