Introduce DRM_BRIDGE_OP_DP, a new bridge operation flag for bridges
that provide DisplayPort connector operations with link training support.
Bridges advertising this flag must fill the dp_link_caps field in
struct drm_bridge with their link capabilities.

In drm_bridge_connector_init(), when a bridge sets DRM_BRIDGE_OP_DP,
use drmm_connector_dp_init() instead of the generic drmm_connector_init()
so the connector exposes link training state properties to userspace.
This mirrors the existing pattern used for HDMI bridges.

Signed-off-by: Kory Maincent <[email protected]>
---
 drivers/gpu/drm/display/drm_bridge_connector.c | 24 ++++++++++++++++++++++++
 include/drm/drm_bridge.h                       | 13 +++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c 
b/drivers/gpu/drm/display/drm_bridge_connector.c
index cafa498c38482..6ea4d45e3146b 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/drivers/gpu/drm/display/drm_bridge_connector.c
@@ -108,6 +108,13 @@ struct drm_bridge_connector {
         * HDMI Audio infrastructure, if any (see &DRM_BRIDGE_OP_HDMI_AUDIO).
         */
        struct drm_bridge *bridge_hdmi_audio;
+       /**
+        * @bridge_dp:
+        *
+        * The bridge in the chain that implements necessary support for the
+        * DisplayPort connector infrastructure, if any (see &DRM_BRIDGE_OP_DP).
+        */
+       struct drm_bridge *bridge_dp;
        /**
         * @bridge_dp_audio:
         *
@@ -773,6 +780,7 @@ static void drm_bridge_connector_put_bridges(struct 
drm_device *dev, void *data)
        drm_bridge_put(bridge_connector->bridge_hdmi_audio);
        drm_bridge_put(bridge_connector->bridge_dp_audio);
        drm_bridge_put(bridge_connector->bridge_hdmi_cec);
+       drm_bridge_put(bridge_connector->bridge_dp);
 }
 
 /**
@@ -908,6 +916,15 @@ struct drm_connector *drm_bridge_connector_init(struct 
drm_device *drm,
                        bridge_connector->bridge_hdmi_audio = 
drm_bridge_get(bridge);
                }
 
+               if (bridge->ops & DRM_BRIDGE_OP_DP) {
+                       if (bridge_connector->bridge_dp)
+                               return ERR_PTR(-EBUSY);
+                       if (!bridge->dp_link_caps)
+                               return ERR_PTR(-EINVAL);
+
+                       bridge_connector->bridge_dp = drm_bridge_get(bridge);
+               }
+
                if (bridge->ops & DRM_BRIDGE_OP_DP_AUDIO) {
                        if (bridge_connector->bridge_dp_audio)
                                return ERR_PTR(-EBUSY);
@@ -996,6 +1013,13 @@ struct drm_connector *drm_bridge_connector_init(struct 
drm_device *drm,
                                               max_bpc);
                if (ret)
                        return ERR_PTR(ret);
+       } else if (bridge_connector->bridge_dp) {
+               ret = drmm_connector_dp_init(drm, connector,
+                                            &drm_bridge_connector_funcs,
+                                            
bridge_connector->bridge_dp->dp_link_caps,
+                                            connector_type, ddc);
+               if (ret)
+                       return ERR_PTR(ret);
        } else {
                ret = drmm_connector_init(drm, connector,
                                          &drm_bridge_connector_funcs,
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 4ba3a5deef9a6..02411e0b71c35 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1092,6 +1092,14 @@ enum drm_bridge_ops {
         * &drm_bridge_funcs->hdmi_clear_spd_infoframe callbacks.
         */
        DRM_BRIDGE_OP_HDMI_SPD_INFOFRAME = BIT(10),
+       /**
+        * @DRM_BRIDGE_OP_DP: The bridge provides DisplayPort connector
+        * operations, including link training support. Bridges that set
+        * this flag must provide DisplayPort-related information and
+        * fill the &drm_bridge->dp_link_train_caps link training
+        * capabilities.
+        */
+       DRM_BRIDGE_OP_DP = BIT(11),
 };
 
 /**
@@ -1267,6 +1275,11 @@ struct drm_bridge {
         */
        void *hpd_data;
 
+       /**
+        * @dp_link_caps: DisplayPort link capabilities
+        */
+       const struct drm_connector_dp_link_caps *dp_link_caps;
+
        /**
         * @next_bridge: Pointer to the following bridge, automatically put
         * when this bridge is freed (i.e. at destroy time). This is for

-- 
2.43.0

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