Hello, On Fri, Jul 17, 2026 at 03:23:19PM +0800, Chaoyi Chen wrote: > From: Chaoyi Chen <[email protected]> > > The HPD function of Type-C DP is implemented through > drm_connector_oob_hotplug_event(). For embedded DP, it is required > that the DRM connector fwnode corresponds to the Type-C port fwnode. > > To describe the relationship between the DP controller and the Type-C > port device, we usually using drm_bridge to build a bridge chain. > > Now several USB-C controller drivers have already implemented the DP > HPD bridge function provided by aux-hpd-bridge.c, it will build a DP > HPD bridge on USB-C connector port device. > > But this requires the USB-C controller driver to manually register the > HPD bridge. If the driver does not implement this feature, the bridge > will not be create. > > So this patch implements a generic DP HPD bridge based on > aux-hpd-bridge.c. It will monitor Type-C bus events, and when a > Type-C port device containing the DP svid is registered, it will > create an HPD bridge for it without the need for the USB-C controller > driver to implement it. > > Signed-off-by: Chaoyi Chen <[email protected]> > Reviewed-by: Heikki Krogerus <[email protected]> > Reviewed-by: Nicolas Frattaroli <[email protected]> > ---
Reviewed-by: Sebastian Reichel <[email protected]> Tested-by: Sebastian Reichel <[email protected]> # ArmSom Sige5 I gave this a test together with the RK3588/RK3576 USB-C DP AltMode patches I'm working on. As the fusb302 does a manual registration for the DRM bridge in its probe function, the bridge is registered twice: root@sige5 # cat /sys/kernel/debug/dri/bridges ... bridge[1]: drm_aux_hpd_bridge_funcs refcount: 4 type: [10] DP OF: /soc/i2c@2ac50000/typec-portc@22/connector:usb-c-connector ops: [0x4] hpd bridge[2]: drm_aux_hpd_bridge_funcs refcount: 2 type: [10] DP OF: /soc/i2c@2ac50000/typec-portc@22/connector:usb-c-connector ops: [0x4] hpd ... Apparently the USB-C DP AltMode keeps working, so this just wastes a few CPU cycles and some memory. So this can land and then we can remove the manual code from the driver as a follow-up step. I also gave that a try and things keep working. I won't send the fusb302 patch for now to ensure its not applied before this patch lands. Greetings, -- Sebastian > (no changes since v3) > > Changes in v2: > - Add copyright text. > - Remove useless goto. > > --- > drivers/gpu/drm/bridge/Kconfig | 10 ++++ > drivers/gpu/drm/bridge/Makefile | 1 + > .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c | 54 +++++++++++++++++++ > 3 files changed, 65 insertions(+) > 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 4a57d49b4c6d..9739b2a19758 100644 > --- a/drivers/gpu/drm/bridge/Kconfig > +++ b/drivers/gpu/drm/bridge/Kconfig > @@ -30,6 +30,16 @@ config DRM_AUX_HPD_BRIDGE > Simple bridge that terminates the bridge chain and provides HPD > support. > > +if DRM_AUX_HPD_BRIDGE > +config DRM_AUX_HPD_TYPEC_BRIDGE > + tristate > + depends on TYPEC || !TYPEC > + default TYPEC > + help > + Simple bridge that terminates the bridge chain and provides HPD > + support. It build bridge on each USB-C connector device node. > +endif > + > menu "Display Interface Bridges" > depends on DRM && DRM_BRIDGE > > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile > index 15cc821d85b7..d88a9e1ccc9a 100644 > --- a/drivers/gpu/drm/bridge/Makefile > +++ b/drivers/gpu/drm/bridge/Makefile > @@ -1,6 +1,7 @@ > # SPDX-License-Identifier: GPL-2.0 > obj-$(CONFIG_DRM_AUX_BRIDGE) += aux-bridge.o > obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) += aux-hpd-bridge.o > +obj-$(CONFIG_DRM_AUX_HPD_TYPEC_BRIDGE) += aux-hpd-typec-dp-bridge.o > obj-$(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-typec-dp-bridge.c > b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c > new file mode 100644 > index 000000000000..c09579ff7ab9 > --- /dev/null > +++ b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c > @@ -0,0 +1,54 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* > + * Copyright (C) 2026 Rockchip Electronics Co., Ltd. > + * > + * Author: Chaoyi Chen <[email protected]> > + */ > +#include <linux/of.h> > +#include <linux/usb/typec_altmode.h> > +#include <linux/usb/typec_dp.h> > + > +#include <drm/bridge/aux-bridge.h> > + > +static int drm_typec_bus_event(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct device *dev = (struct device *)data; > + struct typec_altmode *alt = to_typec_altmode(dev); > + > + if (action != BUS_NOTIFY_ADD_DEVICE) > + return NOTIFY_OK; > + > + /* > + * alt->dev.parent->parent : USB-C controller device > + * alt->dev.parent : USB-C connector device > + */ > + if (is_typec_port_altmode(&alt->dev) && alt->svid == USB_TYPEC_DP_SID) > + drm_dp_hpd_bridge_register(alt->dev.parent->parent, > + to_of_node(alt->dev.parent->fwnode)); > + > + return NOTIFY_OK; > +} > + > +static struct notifier_block drm_typec_event_nb = { > + .notifier_call = drm_typec_bus_event, > +}; > + > +static void drm_aux_hpd_typec_dp_bridge_module_exit(void) > +{ > + bus_unregister_notifier(&typec_bus, &drm_typec_event_nb); > +} > + > +static int __init drm_aux_hpd_typec_dp_bridge_module_init(void) > +{ > + bus_register_notifier(&typec_bus, &drm_typec_event_nb); > + > + return 0; > +} > + > +module_init(drm_aux_hpd_typec_dp_bridge_module_init); > +module_exit(drm_aux_hpd_typec_dp_bridge_module_exit); > + > +MODULE_AUTHOR("Chaoyi Chen <[email protected]>"); > +MODULE_DESCRIPTION("DRM TYPEC DP HPD BRIDGE"); > +MODULE_LICENSE("GPL"); > -- > 2.53.0 >
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