drm/bridge: Provide a helper to retrieve current bridge state

The current bridge state is accessible from the drm_bridge structure,
but since it's fairly indirect it's not easy to figure out.

Provide a helper to retrieve it.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250313-bridge-connector-v6-2-511c54a604fb@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 884ff1faa4c8..cdad3b78a195 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -958,6 +958,38 @@ static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 #endif
 
 /**
+ * drm_bridge_get_current_state() - Get the current bridge state
+ * @bridge: bridge object
+ *
+ * This function must be called with the modeset lock held.
+ *
+ * RETURNS:
+ *
+ * The current bridge state, or NULL if there is none.
+ */
+static inline struct drm_bridge_state *
+drm_bridge_get_current_state(struct drm_bridge *bridge)
+{
+	if (!bridge)
+		return NULL;
+
+	/*
+	 * Only atomic bridges will have bridge->base initialized by
+	 * drm_atomic_private_obj_init(), so we need to make sure we're
+	 * working with one before we try to use the lock.
+	 */
+	if (!bridge->funcs || !bridge->funcs->atomic_reset)
+		return NULL;
+
+	drm_modeset_lock_assert_held(&bridge->base.lock);
+
+	if (!bridge->base.state)
+		return NULL;
+
+	return drm_priv_to_bridge_state(bridge->base.state);
+}
+
+/**
  * drm_bridge_get_next_bridge() - Get the next bridge in the chain
  * @bridge: bridge object
  *