drm/bridge: analogix_dp: Add new API analogix_dp_finish_probe()

Since the panel/bridge should logically be positioned behind the
Analogix bridge in the display pipeline, it makes sense to handle
the panel/bridge parsing on the Analogix side. Therefore, we add
a new API analogix_dp_finish_probe(), which combines the panel/bridge
parsing with component addition, to do it.

In order to process component binding right after the probe completes,
the &analogix_dp_plat_data.ops is newly added to pass &component_ops,
for which the &dp_aux_ep_device_with_data.done_probing() of DP AUX bus
only supports passing &drm_dp_aux.

Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Heiko Stuebner <heiko@sntech.de> # rk3588
Link: https://patch.msgid.link/20260413132551.1049307-4-damon.ding@rock-chips.com
[Luca: propagate 'depends on OF' to DRM_ANALOGIX_DP and reverse dependencies]
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

drivers/gpu/drm/bridge/analogix/Kconfig

@@ -15,6 +15,7 @@ config DRM_ANALOGIX_ANX6345
 
 config DRM_ANALOGIX_ANX78XX
 	tristate "Analogix ANX78XX bridge"
+	depends on OF
 	select DRM_ANALOGIX_DP
 	select DRM_DISPLAY_DP_HELPER
 	select DRM_DISPLAY_HELPER
@@ -29,6 +30,8 @@ config DRM_ANALOGIX_ANX78XX
 config DRM_ANALOGIX_DP
 	tristate
 	depends on DRM
+	depends on OF
+	select DRM_DISPLAY_DP_AUX_BUS
 
 config DRM_ANALOGIX_ANX7625
 	tristate "Analogix Anx7625 MIPI to DP interface support"

drivers/gpu/drm/bridge/analogix/analogix_dp_core.c

@@ -21,12 +21,14 @@
 #include <linux/platform_device.h>
 
 #include <drm/bridge/analogix_dp.h>
+#include <drm/display/drm_dp_aux_bus.h>
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
@@ -1582,6 +1584,50 @@ struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp)
 }
 EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
 
+static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
+{
+	struct analogix_dp_device *dp = to_dp(aux);
+	struct analogix_dp_plat_data *plat_data = dp->plat_data;
+	int port = plat_data->dev_type == EXYNOS_DP ? 0 : 1;
+	int ret;
+
+	/*
+	 * If drm_of_find_panel_or_bridge() returns -ENODEV, there may be no valid panel
+	 * or bridge nodes. The driver should go on for the driver-free bridge or the DP
+	 * mode applications.
+	 */
+	ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
+					  &plat_data->panel, &plat_data->next_bridge);
+	if (ret && ret != -ENODEV)
+		return ret;
+
+	return component_add(dp->dev, plat_data->ops);
+}
+
+int analogix_dp_finish_probe(struct analogix_dp_device *dp)
+{
+	int ret;
+
+	ret = devm_of_dp_aux_populate_bus(&dp->aux, analogix_dp_aux_done_probing);
+	if (ret) {
+		/*
+		 * If devm_of_dp_aux_populate_bus() returns -ENODEV, the done_probing() will
+		 * not be called because there are no EP devices. Then the callback function
+		 * analogix_dp_aux_done_probing() will be called directly in order to support
+		 * the other valid DT configurations.
+		 *
+		 * NOTE: The devm_of_dp_aux_populate_bus() is allowed to return -EPROBE_DEFER.
+		 */
+		if (ret != -ENODEV)
+			return dev_err_probe(dp->dev, ret, "failed to populate aux bus\n");
+
+		return analogix_dp_aux_done_probing(&dp->aux);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(analogix_dp_finish_probe);
+
 MODULE_AUTHOR("Jingoo Han <jg1.han@samsung.com>");
 MODULE_DESCRIPTION("Analogix DP Core Driver");
 MODULE_LICENSE("GPL v2");

drivers/gpu/drm/exynos/Kconfig

@@ -69,6 +69,7 @@ config DRM_EXYNOS_DSI
 config DRM_EXYNOS_DP
 	bool "Exynos specific extensions for Analogix DP driver"
 	depends on DRM_EXYNOS_FIMD || DRM_EXYNOS7_DECON
+	depends on OF
 	select DRM_ANALOGIX_DP
 	select DRM_BRIDGE_CONNECTOR
 	select DRM_DISPLAY_DP_HELPER

include/drm/bridge/analogix_dp.h

@@ -30,6 +30,7 @@ struct analogix_dp_plat_data {
 	struct drm_bridge *next_bridge;
 	struct drm_encoder *encoder;
 	struct drm_connector *connector;
+	const struct component_ops *ops;
 
 	int (*power_on)(struct analogix_dp_plat_data *);
 	int (*power_off)(struct analogix_dp_plat_data *);
@@ -49,5 +50,6 @@ int analogix_dp_stop_crc(struct drm_connector *connector);
 
 struct analogix_dp_plat_data *analogix_dp_aux_to_plat_data(struct drm_dp_aux *aux);
 struct drm_dp_aux *analogix_dp_get_aux(struct analogix_dp_device *dp);
+int analogix_dp_finish_probe(struct analogix_dp_device *dp);
 
 #endif /* _ANALOGIX_DP_H_ */