usb: typec: altmodes/displayport: Notify drm subsys of hotplug events

Use the new drm_connector_oob_hotplug_event() functions to let drm/kms
drivers know about DisplayPort over Type-C hotplug events.

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20210817215201.795062-9-hdegoede@redhat.com

drivers/usb/typec/altmodes/Kconfig

@@ -4,6 +4,7 @@ menu "USB Type-C Alternate Mode drivers"
 
 config TYPEC_DP_ALTMODE
 	tristate "DisplayPort Alternate Mode driver"
+	depends on DRM
 	help
 	  DisplayPort USB Type-C Alternate Mode allows DisplayPort
 	  displays and adapters to be attached to the USB Type-C

drivers/usb/typec/altmodes/displayport.c

@@ -11,8 +11,10 @@
 #include <linux/delay.h>
 #include <linux/mutex.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/usb/pd_vdo.h>
 #include <linux/usb/typec_dp.h>
+#include <drm/drm_connector.h>
 #include "displayport.h"
 
 #define DP_HEADER(_dp, ver, cmd)	(VDO((_dp)->alt->svid, 1, ver, cmd)	\
@@ -57,11 +59,13 @@ struct dp_altmode {
 	struct typec_displayport_data data;
 
 	enum dp_state state;
+	bool hpd;
 
 	struct mutex lock; /* device lock */
 	struct work_struct work;
 	struct typec_altmode *alt;
 	const struct typec_altmode *port;
+	struct fwnode_handle *connector_fwnode;
 };
 
 static int dp_altmode_notify(struct dp_altmode *dp)
@@ -125,6 +129,7 @@ static int dp_altmode_configure(struct dp_altmode *dp, u8 con)
 static int dp_altmode_status_update(struct dp_altmode *dp)
 {
 	bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
+	bool hpd = !!(dp->data.status & DP_STATUS_HPD_STATE);
 	u8 con = DP_STATUS_CONNECTION(dp->data.status);
 	int ret = 0;
 
@@ -137,6 +142,11 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
 		ret = dp_altmode_configure(dp, con);
 		if (!ret)
 			dp->state = DP_STATE_CONFIGURE;
+	} else {
+		if (dp->hpd != hpd) {
+			drm_connector_oob_hotplug_event(dp->connector_fwnode);
+			dp->hpd = hpd;
+		}
 	}
 
 	return ret;
@@ -512,6 +522,7 @@ static const struct attribute_group dp_altmode_group = {
 int dp_altmode_probe(struct typec_altmode *alt)
 {
 	const struct typec_altmode *port = typec_altmode_get_partner(alt);
+	struct fwnode_handle *fwnode;
 	struct dp_altmode *dp;
 	int ret;
 
@@ -540,6 +551,11 @@ int dp_altmode_probe(struct typec_altmode *alt)
 	alt->desc = "DisplayPort";
 	alt->ops = &dp_altmode_ops;
 
+	fwnode = dev_fwnode(alt->dev.parent->parent); /* typec_port fwnode */
+	dp->connector_fwnode = fwnode_find_reference(fwnode, "displayport", 0);
+	if (IS_ERR(dp->connector_fwnode))
+		dp->connector_fwnode = NULL;
+
 	typec_altmode_set_drvdata(alt, dp);
 
 	dp->state = DP_STATE_ENTER;
@@ -555,6 +571,13 @@ void dp_altmode_remove(struct typec_altmode *alt)
 
 	sysfs_remove_group(&alt->dev.kobj, &dp_altmode_group);
 	cancel_work_sync(&dp->work);
+
+	if (dp->connector_fwnode) {
+		if (dp->hpd)
+			drm_connector_oob_hotplug_event(dp->connector_fwnode);
+
+		fwnode_handle_put(dp->connector_fwnode);
+	}
 }
 EXPORT_SYMBOL_GPL(dp_altmode_remove);