[PATCH 4/9] drm/connector: Add support for out-of-band hotplug notification (v2)

Hans de Goede
2021-05-03T15:47:13Z

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.

Changes in v2:
- Make drm_connector_oob_hotplug_event() take a fwnode as argument and
have it call drm_connector_find_by_fwnode() internally. This allows
making drm_connector_find_by_fwnode() a drm-internal function and
avoids code outside the drm subsystem potentially holding on the
a drm_connector reference for a longer period.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/gpu/drm/drm_connector.c | 29 +++++++++++++++++++++++++++++
include/drm/drm_connector.h | 33 +++++++++++++++++++++++++++++++++
2 files changed, 62 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index ef759d6add81..b5e09d751694 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2726,6 +2726,35 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
return found;
}

+/**
+ * drm_connector_oob_hotplug_event - Report out-of-band hotplug event to connector
+ * @connector: connector to report the event on
+ * @data: data related to the event
+ *
+ * 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 drm_connector_oob_hotplug_event_data *data)
+{
+ struct drm_connector *connector;
+
+ connector = drm_connector_find_by_fwnode(connector_fwnode);
+ if (IS_ERR(connector))
+ return;
+
+ if (connector->funcs->oob_hotplug_event)
+ connector->funcs->oob_hotplug_event(connector, data);
+
+ drm_connector_put(connector);
+}
+EXPORT_SYMBOL(drm_connector_oob_hotplug_event);
+

/**
* DOC: Tile group
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index ae377354e48e..bb61aeb9ba2d 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -27,6 +27,7 @@
#include <linux/llist.h>
#include <linux/ctype.h>
#include <linux/hdmi.h>
+#include <linux/usb/typec.h> /* For enum typec_orientation */
#include <drm/drm_mode_object.h>
#include <drm/drm_util.h>

@@ -649,6 +650,27 @@ struct drm_connector_tv_margins {
unsigned int top;
};

+/**
+ * struct drm_connector_oob_hotplug_event_data: OOB hotplug event data
+ *
+ * Contains data about out-of-band hotplug events, signalled through
+ * drm_connector_oob_hotplug_event().
+ */
+struct drm_connector_oob_hotplug_event_data {
+ /**
+ * @connected: New connected status for the connector.
+ */
+ bool connected;
+ /**
+ * @dp_lanes: Number of available displayport lanes, 0 if unknown.
+ */
+ int dp_lanes;
+ /**
+ * @orientation: Connector orientation.
+ */
+ enum typec_orientation orientation;
+};
+
/**
* struct drm_tv_connector_state - TV connector related states
* @subconnector: selected subconnector
@@ -1110,6 +1132,15 @@ struct drm_connector_funcs {
*/
void (*atomic_print_state)(struct drm_printer *p,
const struct drm_connector_state *state);
+
+ /**
+ * @oob_hotplug_event:
+ *
+ * This will get called when a hotplug-event for a drm-connector
+ * has been received from a source outside the display driver / device.
+ */
+ void (*oob_hotplug_event)(struct drm_connector *connector,
+ struct drm_connector_oob_hotplug_event_data *data);
};

/**
@@ -1704,6 +1735,8 @@ drm_connector_is_unregistered(struct drm_connector *connector)
DRM_CONNECTOR_UNREGISTERED;
}

+void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
+ struct drm_connector_oob_hotplug_event_data *data);
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);
--
2.31.1