[PATCH v2 1/2] drm/bridge/panel: Add drm_bridge_get_panel to extract panel from last bridge

[Marek Vasut <marex@denx.de>]

Add drm_bridge_get_panel() function to extract drm_panel pointer from
panel_bridge. This can be used by bridges in the middle to look up and
access drm_panel at the end, and e.g. extract display_timings from it.

Signed-off-by: Marek Vasut <marex@denx.de>
---
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: David Airlie <airlied@gmail.com>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Cc: Robert Foss <rfoss@kernel.org>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: dri-devel@lists.freedesktop.org
---
V2: - New patch
---
 drivers/gpu/drm/bridge/panel.c | 18 ++++++++++++++++++
 include/drm/drm_bridge.h       |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
index 6e88339dec0f5..0e5937dc7ab21 100644
--- a/drivers/gpu/drm/bridge/panel.c
+++ b/drivers/gpu/drm/bridge/panel.c
@@ -235,6 +235,24 @@ bool drm_bridge_is_panel(const struct drm_bridge *bridge)
 }
 EXPORT_SYMBOL(drm_bridge_is_panel);
 
+/**
+ * drm_bridge_get_panel - Return panel if a drm_bridge is a panel_bridge.
+ *
+ * @bridge: The drm_bridge.
+ *
+ * Returns drm_panel pointer if the bridge is a panel bridge, or NULL otherwise.
+ */
+struct drm_panel *drm_bridge_get_panel(struct drm_bridge *bridge)
+{
+	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
+
+	if (!drm_bridge_is_panel(bridge))
+		return NULL;
+
+	return panel_bridge->panel;
+}
+EXPORT_SYMBOL(drm_bridge_get_panel);
+
 /**
  * drm_panel_bridge_add - Creates a &drm_bridge and &drm_connector that
  * just calls the appropriate functions from &drm_panel.
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index e8d735b7f6a48..4b64ab47c9d7f 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -984,6 +984,7 @@ void drm_bridge_hpd_notify(struct drm_bridge *bridge,
 
 #ifdef CONFIG_DRM_PANEL_BRIDGE
 bool drm_bridge_is_panel(const struct drm_bridge *bridge);
+struct drm_panel *drm_bridge_get_panel(struct drm_bridge *bridge);
 struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel);
 struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel,
 					      u32 connector_type);
@@ -1004,6 +1005,11 @@ static inline bool drm_bridge_is_panel(const struct drm_bridge *bridge)
 	return false;
 }
 
+static struct drm_panel *drm_bridge_get_panel(struct drm_bridge *bridge)
+{
+	return NULL;
+}
+
 static inline int drm_panel_bridge_set_orientation(struct drm_connector *connector,
 						   struct drm_bridge *bridge)
 {
-- 
2.45.2