drm/crtc-helper: Add a drm_crtc_helper_atomic_check() helper

Provides a default CRTC state check handler for CRTCs that only have one
primary plane attached.

There are some drivers that duplicate this logic in their helpers, such as
simpledrm and ssd130x. Factor out this common code into a CRTC helper and
make drivers use it.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20221011165136.469750-5-javierm@redhat.com

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 457448cc60f7..1f0a270ac984 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -421,6 +421,32 @@ done:
 }
 EXPORT_SYMBOL(drm_crtc_helper_set_mode);
 
+/**
+ * drm_crtc_helper_atomic_check() - Helper to check CRTC atomic-state
+ * @crtc: CRTC to check
+ * @state: atomic state object
+ *
+ * Provides a default CRTC-state check handler for CRTCs that only have
+ * one primary plane attached to it.
+ *
+ * This is often the case for the CRTC of simple framebuffers. See also
+ * drm_plane_helper_atomic_check() for the respective plane-state check
+ * helper function.
+ *
+ * RETURNS:
+ * Zero on success, or an errno code otherwise.
+ */
+int drm_crtc_helper_atomic_check(struct drm_crtc *crtc, struct drm_atomic_state *state)
+{
+	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+
+	if (!new_crtc_state->enable)
+		return 0;
+
+	return drm_atomic_helper_check_crtc_primary_plane(new_crtc_state);
+}
+EXPORT_SYMBOL(drm_crtc_helper_atomic_check);
+
 static void
 drm_crtc_helper_disable(struct drm_crtc *crtc)
 {