[PATCH v5 1/8] usb: typec: Add default HPD device when register DisplayPort altmode

Chaoyi Chen
2025-10-11T03:33:18Z

From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

Add default DRM AUX HPD bridge device when register DisplayPort
altmode. That makes it redundant for each Type-C driver to implement
a similar registration process in embedded scenarios.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
---

Changes in v5:
- Remove the calls related to `drm_aux_hpd_bridge_notify()`.
- Place the helper functions in the same compilation unit.
- Add more comments about parent device.

drivers/usb/typec/class.c | 26 ++++++++++++++++++++++++++
include/linux/usb/typec_altmode.h | 2 ++
2 files changed, 28 insertions(+)

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 67a533e35150..e9d7772d1a8f 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -8,14 +8,18 @@

#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/of.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/string_choices.h>
#include <linux/usb/pd_vdo.h>
+#include <linux/usb/typec_dp.h>
#include <linux/usb/typec_mux.h>
#include <linux/usb/typec_retimer.h>
#include <linux/usb.h>

+#include <drm/bridge/aux-bridge.h>
+
#include "bus.h"
#include "class.h"
#include "pd.h"
@@ -538,6 +542,21 @@ const struct device_type typec_altmode_dev_type = {
.release = typec_altmode_release,
};

+static void dp_altmode_hpd_device_register(struct typec_altmode *alt)
+{
+ if (alt->svid != USB_TYPEC_DP_SID)
+ return;
+
+ /*
+ * alt->dev.parent->parent : USB-C controller device
+ * alt->dev.parent : USB-C connector device
+ */
+ alt->hpd_dev = drm_dp_hpd_bridge_register(alt->dev.parent->parent,
+ to_of_node(alt->dev.parent->fwnode));
+ if (IS_ERR(alt->hpd_dev))
+ alt->hpd_dev = NULL;
+}
+
static struct typec_altmode *
typec_register_altmode(struct device *parent,
const struct typec_altmode_desc *desc)
@@ -600,6 +619,13 @@ typec_register_altmode(struct device *parent,
return ERR_PTR(ret);
}

+ /*
+ * It is too late to register the HPD device when the DisplayPort
+ * altmode device becomes ready. If the current altmode is DP,
+ * register a static HPD device.
+ */
+ dp_altmode_hpd_device_register(&alt->adev);
+
return &alt->adev;
}

diff --git a/include/linux/usb/typec_altmode.h b/include/linux/usb/typec_altmode.h
index b3c0866ea70f..acb0af1b9d5d 100644
--- a/include/linux/usb/typec_altmode.h
+++ b/include/linux/usb/typec_altmode.h
@@ -21,6 +21,7 @@ struct typec_altmode_ops;
* @desc: Optional human readable description of the mode
* @ops: Operations vector from the driver
* @cable_ops: Cable operations vector from the driver.
+ * @hpd_dev: HPD device for DisplayPort
*/
struct typec_altmode {
struct device dev;
@@ -32,6 +33,7 @@ struct typec_altmode {
char *desc;
const struct typec_altmode_ops *ops;
const struct typec_cable_ops *cable_ops;
+ struct device *hpd_dev;
};

#define to_typec_altmode(d) container_of(d, struct typec_altmode, dev)
--
2.49.0