drm: More links for gamma support helpers

It's not obvious that when using the new color manager stuff you still
need to wire up the legacy helper to get legacy LUT support. Improve
this with more links. drm_crtc_funcs->gamma_set already explains this
properly.

Cc: Peter Rosin <peda@axentia.se>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170620094228.4757-1-daniel.vetter@ffwll.ch

diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index 3eda500fc005ea485b4c5ed52bc19bead9a23814..fe0982708e9528cdaaaca6cd1e1996558c4a0806 100644 (file)
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -128,6 +128,9 @@ EXPORT_SYMBOL(drm_color_lut_extract);
  * optional. The gamma and degamma properties are only attached if
  * their size is not 0 and ctm_property is only attached if has_ctm is
  * true.
+ *
+ * Drivers should use drm_atomic_helper_legacy_gamma_set() to implement the
+ * legacy &drm_crtc_funcs.gamma_set callback.
  */
 void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
                                uint degamma_lut_size,