[PATCH RFC v3 8/8] drm/mediatek: Use dp_connector helpers to expose link training state

[Kory Maincent <kory.maincent@bootlin.com>]

Adopt the DRM core DisplayPort helpers by setting DRM_BRIDGE_OP_DP and
populating the bridge dp_link_caps at probe time. Report the sink
capabilities on hotplug, reset them on disconnect, and report the link
parameters once link training succeeds.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
---
Not tested. I believed I had a board with this device, but it actually uses
an anx7625 bridge. I'm unable to test it; it would be appreciated if
someone else could, so the change isn't dropped.

Changes in v3:
- Sync and report sink capabilities from the HPD thread for DisplayPort,
  or in atomic_enable for eDP. Reset them on unplug, or atomic disable
  and only report link parameters after successful training.
- Add connection_mutex lock for DisplayPort in the IRQ thread.

Changes in v2:
- Remove voltage swing and pre emphasis properties.
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 79 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 75 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index f656b85b84212..2e2596eaa342e 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1812,6 +1812,35 @@ static void mtk_dp_train_change_mode(struct mtk_dp *mtk_dp)
 	mtk_dp_reset_swing_pre_emphasis(mtk_dp);
 }
 
+static void _mtk_dp_report_link_train(struct mtk_dp *mtk_dp)
+{
+	u32 rate, nlanes;
+	bool dsc = false;
+
+	rate = drm_dp_bw_code_to_link_rate(mtk_dp->train_info.link_rate);
+	nlanes = mtk_dp->train_info.lane_count;
+
+	drm_dp_set_cur_link_params(mtk_dp->conn, rate, nlanes, dsc);
+}
+
+static void mtk_dp_report_link_train(struct mtk_dp *mtk_dp)
+{
+	struct drm_modeset_lock *lock;
+	int ret;
+
+	if (!mtk_dp->conn)
+		return;
+
+	lock = &mtk_dp->conn->dev->mode_config.connection_mutex;
+	ret = drm_modeset_lock_single_interruptible(lock);
+	if (ret)
+		return;
+
+	_mtk_dp_report_link_train(mtk_dp);
+
+	drm_modeset_unlock(lock);
+}
+
 static int mtk_dp_training(struct mtk_dp *mtk_dp)
 {
 	int ret;
@@ -2015,6 +2044,8 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
 			ret = mtk_dp_training(mtk_dp);
 			if (ret)
 				drm_err(mtk_dp->drm_dev, "Training failed, %d\n", ret);
+			else
+				mtk_dp_report_link_train(mtk_dp);
 
 			mtk_dp->enabled = true;
 		}
@@ -2145,9 +2176,12 @@ mtk_dp_bdg_detect(struct drm_bridge *bridge, struct drm_connector *connector)
 	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
 	enum drm_connector_status ret = connector_status_disconnected;
 	bool enabled = mtk_dp->enabled;
+	int err;
 
-	if (!mtk_dp->train_info.cable_plugged_in)
+	if (!mtk_dp->train_info.cable_plugged_in) {
+		drm_dp_sink_reset_caps(connector);
 		return ret;
+	}
 
 	if (!enabled)
 		mtk_dp_aux_panel_poweron(mtk_dp, true);
@@ -2160,9 +2194,18 @@ mtk_dp_bdg_detect(struct drm_bridge *bridge, struct drm_connector *connector)
 	 * whether we connect to a sink device.
 	 */
 
-	if (drm_dp_read_sink_count(&mtk_dp->aux) > 0)
+	if (drm_dp_read_sink_count(&mtk_dp->aux) > 0) {
 		ret = connector_status_connected;
 
+		err = drm_dp_sink_sync_caps(connector, &mtk_dp->aux, NULL);
+		if (err)
+			drm_dbg_kms(mtk_dp->aux.drm_dev,
+				    "%s: error sink caps synchronisation (%d)\n",
+				    mtk_dp->aux.name, err);
+	} else {
+		drm_dp_sink_reset_caps(connector);
+	}
+
 	if (!enabled)
 		mtk_dp_aux_panel_poweron(mtk_dp, false);
 
@@ -2390,12 +2433,20 @@ static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 	if (mtk_dp->data->bridge_type == DRM_MODE_CONNECTOR_eDP) {
 		mtk_dp_aux_panel_poweron(mtk_dp, true);
 
+		ret = drm_dp_sink_sync_caps(mtk_dp->conn, &mtk_dp->aux, NULL);
+		if (ret)
+			drm_dbg_kms(mtk_dp->aux.drm_dev,
+				    "%s: error sink caps synchronisation (%d)\n",
+				    mtk_dp->aux.name, ret);
+
 		/* Training */
 		ret = mtk_dp_training(mtk_dp);
 		if (ret) {
 			drm_err(mtk_dp->drm_dev, "Training failed, %d\n", ret);
 			goto power_off_aux;
 		}
+
+		_mtk_dp_report_link_train(mtk_dp);
 	}
 
 	ret = mtk_dp_video_config(mtk_dp);
@@ -2435,6 +2486,7 @@ static void mtk_dp_bridge_atomic_disable(struct drm_bridge *bridge,
 	if (mtk_dp->data->bridge_type == DRM_MODE_CONNECTOR_eDP) {
 		mtk_dp->enabled = false;
 		mtk_dp_aux_panel_poweron(mtk_dp, false);
+		drm_dp_sink_reset_caps(mtk_dp->conn);
 	}
 
 	mtk_dp_update_plugged_status(mtk_dp);
@@ -2740,11 +2792,14 @@ static int mtk_dp_edp_link_panel(struct drm_dp_aux *mtk_aux)
 	return 0;
 }
 
+static int mtk_dp_rates[] = {162000, 270000, 540000, 810000};
+
 static int mtk_dp_probe(struct platform_device *pdev)
 {
+	struct drm_connector_dp_link_caps *source_caps;
 	struct mtk_dp *mtk_dp;
 	struct device *dev = &pdev->dev;
-	int ret;
+	int ret, i, max_rate;
 
 	mtk_dp = devm_drm_bridge_alloc(dev, struct mtk_dp, bridge,
 				       &mtk_dp_bridge_funcs);
@@ -2758,6 +2813,20 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to parse dt\n");
 
+	source_caps = devm_kzalloc(dev, sizeof(*source_caps), GFP_KERNEL);
+	if (!source_caps)
+		return -ENOMEM;
+
+	source_caps->nlanes = mtk_dp->max_lanes;
+	source_caps->link_rates = mtk_dp_rates;
+
+	max_rate = drm_dp_bw_code_to_link_rate(mtk_dp->max_linkrate);
+	for (i = 0; i < ARRAY_SIZE(mtk_dp_rates); i++)
+		if (mtk_dp_rates[i] > max_rate)
+			break;
+
+	source_caps->nlink_rates = i;
+
 	/*
 	 * Request the interrupt and install service routine only if we are
 	 * on full DisplayPort.
@@ -2809,6 +2878,8 @@ static int mtk_dp_probe(struct platform_device *pdev)
 
 	mtk_dp->bridge.of_node = dev->of_node;
 	mtk_dp->bridge.type = mtk_dp->data->bridge_type;
+	mtk_dp->bridge.dp_link_caps = source_caps;
+	mtk_dp->bridge.ops = DRM_BRIDGE_OP_DP;
 
 	if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
 		/*
@@ -2849,7 +2920,7 @@ static int mtk_dp_probe(struct platform_device *pdev)
 			}
 		}
 	} else {
-		mtk_dp->bridge.ops = DRM_BRIDGE_OP_DETECT |
+		mtk_dp->bridge.ops |= DRM_BRIDGE_OP_DETECT |
 				     DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
 		ret = devm_drm_bridge_add(dev, &mtk_dp->bridge);
 		if (ret)

-- 
2.43.0