On 11/3/2025 12:00 PM, Dmitry Baryshkov wrote:
On Wed, Oct 29, 2025 at 03:14:28PM +0800, Chaoyi Chen wrote:
From: Chaoyi Chen <[email protected]>
Several USB-C controller drivers have already implemented the DP HPD
bridge function provided by aux-hpd-bridge.c, but there are still
some USB-C controller driver that have not yet implemented it.
This patch implements a generic DP HPD bridge based on aux-hpd-bridge.c,
so that other USB-C controller drivers don't need to implement it again.
This doesn't describe the problem that you are trying to solve.
I'll try to describe the information more accurately. Thank you.
Signed-off-by: Chaoyi Chen <[email protected]>
---
Changes in v8:
- Merge generic DP HPD bridge into one module.
drivers/gpu/drm/bridge/Kconfig | 5 +-
drivers/gpu/drm/bridge/Makefile | 8 +++-
drivers/gpu/drm/bridge/aux-hpd-bridge.c | 23 ++++++++-
drivers/gpu/drm/bridge/aux-hpd-bridge.h | 13 +++++
.../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c | 47 +++++++++++++++++++
5 files changed, 93 insertions(+), 3 deletions(-)
create mode 100644 drivers/gpu/drm/bridge/aux-hpd-bridge.h
create mode 100644 drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index a250afd8d662..17257b223a28 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -23,13 +23,16 @@ config DRM_AUX_BRIDGE
build bridges chain.
config DRM_AUX_HPD_BRIDGE
- tristate
+ tristate "AUX HPD bridge support"
Why? No, this is supposed to be selected by other drivers. Users don't
know an wouldn't know what is this.
In v7, I implemented an additional module for selecting this option. But Heikki
believes that it would be better to merge the two modules into one.
depends on DRM_BRIDGE && OF
select AUXILIARY_BUS
help
Simple bridge that terminates the bridge chain and provides HPD
support.
+ Specifically, if you want a default Type-C DisplayPort HPD bridge for
+ each port of the Type-C controller, say Y here.
+
menu "Display Interface Bridges"
depends on DRM && DRM_BRIDGE
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index c7dc03182e59..2998937444bc 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -1,6 +1,12 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_DRM_AUX_BRIDGE) += aux-bridge.o
-obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) += aux-hpd-bridge.o
+
+hpd-bridge-y := aux-hpd-bridge.o
+ifneq ($(CONFIG_TYPEC),)
+hpd-bridge-y += aux-hpd-typec-dp-bridge.o
+endif
+obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) += hpd-bridge.o
+
obj-$(CONFIG_DRM_CHIPONE_ICN6211) += chipone-icn6211.o
obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
obj-$(CONFIG_DRM_CROS_EC_ANX7688) += cros-ec-anx7688.o
diff --git a/drivers/gpu/drm/bridge/aux-hpd-bridge.c
b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
index 2e9c702c7087..11ad6dc776c7 100644
--- a/drivers/gpu/drm/bridge/aux-hpd-bridge.c
+++ b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
@@ -12,6 +12,8 @@
#include <drm/drm_bridge.h>
#include <drm/bridge/aux-bridge.h>
+#include "aux-hpd-bridge.h"
+
static DEFINE_IDA(drm_aux_hpd_bridge_ida);
struct drm_aux_hpd_bridge_data {
@@ -204,7 +206,26 @@ static struct auxiliary_driver drm_aux_hpd_bridge_drv = {
.id_table = drm_aux_hpd_bridge_table,
.probe = drm_aux_hpd_bridge_probe,
};
-module_auxiliary_driver(drm_aux_hpd_bridge_drv);
+
+static int drm_aux_hpd_bridge_mod_init(void)
+{
+ int ret;
+
+ ret = auxiliary_driver_register(&drm_aux_hpd_bridge_drv);
+ if (ret)
+ return ret;
+
+ return drm_aux_hpd_typec_dp_bridge_init();
+}
+
+static void drm_aux_hpd_bridge_mod_exit(void)
+{
+ drm_aux_hpd_typec_dp_bridge_exit();
+ auxiliary_driver_unregister(&drm_aux_hpd_bridge_drv);
+}
+
+module_init(drm_aux_hpd_bridge_mod_init);
+module_exit(drm_aux_hpd_bridge_mod_exit);
MODULE_AUTHOR("Dmitry Baryshkov <[email protected]>");
MODULE_DESCRIPTION("DRM HPD bridge");
diff --git a/drivers/gpu/drm/bridge/aux-hpd-bridge.h
b/drivers/gpu/drm/bridge/aux-hpd-bridge.h
new file mode 100644
index 000000000000..69364731c2f1
--- /dev/null
+++ b/drivers/gpu/drm/bridge/aux-hpd-bridge.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef AUX_HPD_BRIDGE_H
+#define AUX_HPD_BRIDGE_H
+
+#if IS_REACHABLE(CONFIG_TYPEC)
+int drm_aux_hpd_typec_dp_bridge_init(void);
+void drm_aux_hpd_typec_dp_bridge_exit(void);
+#else
+static inline int drm_aux_hpd_typec_dp_bridge_init(void) { return 0; }
+static inline void drm_aux_hpd_typec_dp_bridge_exit(void) { }
+#endif /* IS_REACHABLE(CONFIG_TYPEC) */
+
+#endif /* AUX_HPD_BRIDGE_H */
diff --git a/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
new file mode 100644
index 000000000000..6f2a1fca0fc5
--- /dev/null
+++ b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <linux/of.h>
+#include <linux/usb/typec_altmode.h>
+#include <linux/usb/typec_dp.h>
+#include <linux/usb/typec_notify.h>
+
+#include <drm/bridge/aux-bridge.h>
+
+#include "aux-hpd-bridge.h"
+
+#if IS_REACHABLE(CONFIG_TYPEC)
+static int drm_typec_bus_event(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
This feels like this should be a part of the Type-C subsystem rather
than DRM.
In v7, this used to be a part of the Type-C subsystem. I'm not sure what Heikki
thinks about this.
+ struct typec_altmode *alt = (struct typec_altmode *)data;
+
+ if (action != TYPEC_ALTMODE_REGISTERED)
+ goto done;
+
+ if (is_typec_partner(&alt->dev) || alt->svid != USB_TYPEC_DP_SID)
+ goto done;
+
+ /*
+ * alt->dev.parent->parent : USB-C controller device
+ * alt->dev.parent : USB-C connector device
+ */
+ drm_dp_hpd_bridge_register(alt->dev.parent->parent,
+ to_of_node(alt->dev.parent->fwnode));
+
+done:
+ return NOTIFY_OK;
+}
+
+static struct notifier_block drm_typec_event_nb = {
+ .notifier_call = drm_typec_bus_event,
+};
+
+int drm_aux_hpd_typec_dp_bridge_init(void)
+{
+ return typec_altmode_register_notify(&drm_typec_event_nb);
+}
+
+void drm_aux_hpd_typec_dp_bridge_exit(void)
+{
+ typec_altmode_unregister_notify(&drm_typec_event_nb);
+}
+#endif
--
2.49.0
--
Best,
Chaoyi
