[PATCH RFC v3 6/8] drm/bridge: Expose link training state via new DRM_BRIDGE_OP_DP flag

[Kory Maincent]

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.

Signed-off-by: Kory Maincent <kory.maincent at bootlin.com>
---
Changes in v3:
- Mone on from drmm_connector_dp_init() to drm_dp_source_set_caps().

Change in v2:
- New patch
---
 drivers/gpu/drm/display/Kconfig                |  1 +
 drivers/gpu/drm/display/drm_bridge_connector.c | 29 ++++++++++++++++++++++++++
 include/drm/drm_bridge.h                       | 13 ++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index df09cf9a8ca19..ce2f6d62c76d0 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -19,6 +19,7 @@ config DRM_BRIDGE_CONNECTOR
 	select DRM_DISPLAY_HDMI_AUDIO_HELPER
 	select DRM_DISPLAY_HDMI_CEC_HELPER
 	select DRM_DISPLAY_HDMI_STATE_HELPER
+	select DRM_DISPLAY_DP_HELPER
 	help
 	  DRM connector implementation terminating DRM bridge chains.
 
diff --git a/drivers/gpu/drm/display/drm_bridge_connector.c b/drivers/gpu/drm/display/drm_bridge_connector.c
index 81f3e26f6fdf5..5b58e86da6259 100644
--- a/drivers/gpu/drm/display/drm_bridge_connector.c
+++ b/drivers/gpu/drm/display/drm_bridge_connector.c
@@ -26,6 +26,7 @@
 #include <drm/display/drm_hdmi_cec_helper.h>
 #include <drm/display/drm_hdmi_helper.h>
 #include <drm/display/drm_hdmi_state_helper.h>
+#include <drm/display/drm_dp_helper.h>
 
 /**
  * DOC: overview
@@ -109,6 +110,13 @@ 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:
 	 *
@@ -835,6 +843,7 @@ 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);
 }
 
 /**
@@ -968,6 +977,15 @@ 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);
@@ -1079,6 +1097,17 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
 					       connector_type, ddc);
 		if (ret)
 			return ERR_PTR(ret);
+	} else if (bridge_connector->bridge_dp) {
+		ret = drmm_connector_init(drm, connector,
+					  &drm_bridge_connector_funcs,
+					  connector_type, ddc);
+		if (ret)
+			return ERR_PTR(ret);
+
+		ret = drm_dp_source_set_caps(connector,
+					     bridge_connector->bridge_dp->dp_link_caps);
+		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 1981d24a700d2..d1430b2b72518 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1021,6 +1021,14 @@ 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_caps link training
+	 * capabilities.
+	 */
+	DRM_BRIDGE_OP_DP = BIT(11),
 };
 
 /**
@@ -1214,6 +1222,11 @@ 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