On Wednesday, 4 March 2026 10:41:44 Central European Summer Time 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]> > --- > > (no changes since v14) > > Changes in v13: > - Only register drm dp hpd bridge for typec port altmode device. > > (no changes since v12) > > Changes in v11: > - Switch to using typec bus notifiers. > > (no changes since v10) > > Changes in v9: > - Remove the exposed DRM_AUX_HPD_BRIDGE option, and select > DRM_AUX_HPD_TYPEC_BRIDGE when it is available. > - Add more commit comment about problem background. > > Changes in v8: > - Merge generic DP HPD bridge into one module. > --- > > drivers/gpu/drm/bridge/Kconfig | 10 ++++ > drivers/gpu/drm/bridge/Makefile | 1 + > .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c | 49 +++++++++++++++++++ > 3 files changed, 60 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 a250afd8d662..559487aa09a9 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 c7dc03182e59..a3a0393d2e72 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..d915e0fb0668 > --- /dev/null > +++ b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c > @@ -0,0 +1,49 @@ > +// SPDX-License-Identifier: GPL-2.0+
Having a copyright statement added here is likely required. Something like /* * Copyright (C) 2026 Rockchip Electronics Co., Ltd. * * Author: Chaoyi Chen <[email protected]> */ will suffice. While I hope it's never relevant for a driver this small, explicit copyright statements in this form have a legal effect in some jurisdictions like the US, where by law it automatically dismisses the defense that the copyright holder wasn't known. > +#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; Small nitpick: The explicit (struct device *) cast of data isn't needed here. Just struct device *dev = data; will work fine. The benefit is that if the type of "data" ever changes (e.g. from void *data to const void *data) then we're not silencing a warning/error through an explicit cast. > + struct typec_altmode *alt = to_typec_altmode(dev); > + > + if (action != BUS_NOTIFY_ADD_DEVICE) > + goto done; > + > + /* > + * 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)); > + > +done: > + return NOTIFY_OK; > +} Nitpicking: the "done" label and "goto done" here is redundant. You could remove the label and replace the goto with another "return NOTIFY_OK;". There's no functional change here though. > + > +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_DESCRIPTION("DRM TYPEC DP HPD BRIDGE"); > +MODULE_LICENSE("GPL"); > Feel free to add yourself as MODULE_AUTHOR here. :) With those things changed: Reviewed-by: Nicolas Frattaroli <[email protected]> Kind regards, Nicolas Frattaroli
