drm: apple: dptx: Wait for link config on connect

Should make connect more reliable by avoiding hardcoded waits which are
either to long or too short. In the second case the display can't be
brought up since dcp fails to report any modes during start.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

drivers/gpu/drm/apple/dcp.c

@@ -10,6 +10,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/gpio/consumer.h>
 #include <linux/iommu.h>
+#include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
@@ -254,6 +255,8 @@ int dcp_get_connector_type(struct platform_device *pdev)
 }
 EXPORT_SYMBOL_GPL(dcp_get_connector_type);
 
+#define DPTX_CONNECT_TIMEOUT msecs_to_jiffies(1000)
+
 static int dcp_dptx_connect(struct apple_dcp *dcp, u32 port)
 {
 	int ret = 0;
@@ -281,8 +284,17 @@ static int dcp_dptx_connect(struct apple_dcp *dcp, u32 port)
 	dcp->dptxport[port].connected = true;
 
 	mutex_unlock(&dcp->hpd_mutex);
-	wait_for_completion_timeout(&dcp->dptxport[port].linkcfg_completion,
-				    msecs_to_jiffies(1000));
+	ret = wait_for_completion_timeout(&dcp->dptxport[port].linkcfg_completion,
+				    DPTX_CONNECT_TIMEOUT);
+	if (ret < 0)
+		dev_warn(dcp->dev, "dcp_dptx_connect: port %d link complete failed:%d\n",
+			 port, ret);
+	else
+		dev_dbg(dcp->dev, "dcp_dptx_connect: waited %d ms for link\n",
+			jiffies_to_msecs(DPTX_CONNECT_TIMEOUT - ret));
+
+	usleep_range(5, 10);
+
 	return 0;
 
 out_unlock:
@@ -370,12 +382,6 @@ int dcp_start(struct platform_device *pdev)
 			// necessary on j473/j474 but not on j314c
 			if (connected)
 				dcp_dptx_connect(dcp, 0);
-			/*
-			 * Long sleep necessary to ensure dcp delivers timing
-			 * modes with matched color modes.
-			 * 400ms was sufficient on j473
-			 */
-			msleep(500);
 		}
 	} else if (dcp->phy)
 		dev_warn(dcp->dev, "OS firmware incompatible with dptxport EP\n");

drivers/gpu/drm/apple/dptxep.c

@@ -294,9 +294,14 @@ static int dptxport_call_set_active_lane_count(struct apple_epic_service *servic
 		dptx->phy_ops.dp.set_lanes = 0;
 	}
 
+	dptx->lane_count = lane_count;
+
 	reply->retcode = cpu_to_le32(retcode);
 	reply->lane_count = cpu_to_le64(lane_count);
 
+	if (dptx->lane_count > 0)
+		complete(&dptx->linkcfg_completion);
+
 	return ret;
 }
 
@@ -330,10 +335,9 @@ dptxport_call_will_change_link_config(struct apple_epic_service *service)
 static int
 dptxport_call_did_change_link_config(struct apple_epic_service *service)
 {
-	struct dptx_port *dptx = service->cookie;
 	/* assume the link config did change and wait a little bit */
 	mdelay(10);
-	complete(&dptx->linkcfg_completion);
+
 	return 0;
 }
 

drivers/gpu/drm/apple/dptxep.h

@@ -55,6 +55,7 @@ struct dptx_port {
 	union phy_configure_opts phy_ops;
 	struct phy *atcphy;
 	struct mux_control *mux;
+	u32 lane_count;
 	u32 link_rate, pending_link_rate;
 	u32 drive_settings[2];
 };