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-rw-r--r--include/drm/drm_modeset_helper_vtables.h15
1 files changed, 13 insertions, 2 deletions
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index 361240ca738e..85984b208218 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -165,7 +165,11 @@ struct drm_crtc_helper_funcs {
* allowed.
*
* Atomic drivers which need to inspect and adjust more state should
- * instead use the @atomic_check callback.
+ * instead use the @atomic_check callback, but note that they're not
+ * perfectly equivalent: @mode_valid is called from
+ * drm_atomic_helper_check_modeset(), but @atomic_check is called from
+ * drm_atomic_helper_check_planes(), because originally it was meant for
+ * plane update checks only.
*
* Also beware that userspace can request its own custom modes, neither
* core nor helpers filter modes to the list of probe modes reported by
@@ -547,7 +551,9 @@ struct drm_encoder_helper_funcs {
* allowed.
*
* Atomic drivers which need to inspect and adjust more state should
- * instead use the @atomic_check callback.
+ * instead use the @atomic_check callback. If @atomic_check is used,
+ * this hook isn't called since @atomic_check allows a strict superset
+ * of the functionality of @mode_fixup.
*
* Also beware that userspace can request its own custom modes, neither
* core nor helpers filter modes to the list of probe modes reported by
@@ -734,6 +740,11 @@ struct drm_encoder_helper_funcs {
* update the CRTC to match what the encoder needs for the requested
* connector.
*
+ * Since this provides a strict superset of the functionality of
+ * @mode_fixup (the requested and adjusted modes are both available
+ * through the passed in &struct drm_crtc_state) @mode_fixup is not
+ * called when @atomic_check is implemented.
+ *
* This function is used by the atomic helpers, but it is optional.
*
* NOTE: