drm/rockchip: Add support for out-of-band hotplug notification

Add a new drm_connector_oob_hotplug_event() function and
oob_hotplug_event drm_connector_funcs member.

On some hardware a hotplug event notification may come from outside the
display driver / device. An example of this is some USB Type-C setups
where the hardware muxes the DisplayPort data and aux-lines but does
not pass the altmode HPD status bit to the GPU's DP HPD pin.

In cases like this the new drm_connector_oob_hotplug_event() function can
be used to report these out-of-band events.

Avoid the conflict of GKI, the drm_connector_oob_hotplug_event() is be
completed in rockchip drm driver, not the drm framework.

Signed-off-by: Zhang Yubing <yubing.zhang@rock-chips.com>
Change-Id: I5b1428daa83b0fdb7cf88e95d0b8fde2548d43d8

drivers/gpu/drm/rockchip/rockchip_drm_drv.c

@@ -46,6 +46,32 @@
 static bool is_support_iommu = true;
 static struct drm_driver rockchip_drm_driver;
 
+/**
+ * drm_connector_oob_hotplug_event - Report out-of-band hotplug event to connector
+ * @connector: connector to report the event on
+ *
+ * On some hardware a hotplug event notification may come from outside the display
+ * driver / device. An example of this is some USB Type-C setups where the hardware
+ * muxes the DisplayPort data and aux-lines but does not pass the altmode HPD
+ * status bit to the GPU's DP HPD pin.
+ *
+ * This function can be used to report these out-of-band events after obtaining
+ * a drm_connector reference through calling drm_connector_find_by_fwnode().
+ */
+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
+{
+	struct rockchip_drm_sub_dev *sub_dev;
+
+	if (!connector_fwnode || !connector_fwnode->dev)
+		return;
+
+	sub_dev = rockchip_drm_get_sub_dev(dev_of_node(connector_fwnode->dev));
+
+	if (sub_dev && sub_dev->connector && sub_dev->oob_hotplug_event)
+		sub_dev->oob_hotplug_event(sub_dev->connector);
+}
+EXPORT_SYMBOL(drm_connector_oob_hotplug_event);
+
 uint32_t rockchip_drm_get_bpp(const struct drm_format_info *info)
 {
 	/* use whatever a driver has set */

drivers/gpu/drm/rockchip/rockchip_drm_drv.h

@@ -58,6 +58,7 @@ struct rockchip_drm_sub_dev {
 	struct drm_connector *connector;
 	struct device_node *of_node;
 	void (*loader_protect)(struct drm_encoder *encoder, bool on);
+	void (*oob_hotplug_event)(struct drm_connector *connector);
 };
 
 struct rockchip_sdr2hdr_state {

include/drm/drm_connector.h

@@ -1649,6 +1649,7 @@ drm_connector_is_unregistered(struct drm_connector *connector)
 		DRM_CONNECTOR_UNREGISTERED;
 }
 
+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode);
 const char *drm_get_connector_type_name(unsigned int connector_type);
 const char *drm_get_connector_status_name(enum drm_connector_status status);
 const char *drm_get_subpixel_order_name(enum subpixel_order order);