Re: [PATCH v8 03/10] drm/bridge: Implement generic USB Type-C DP HPD bridge

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

Wed, Oct 29, 2025 at 03:14:28PM +0800, Chaoyi Chen kirjoitti:
> From: Chaoyi Chen <chaoyi.chen@rock-chips.com>
> 
> 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.
> 
> Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
> ---
> 
> 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"

Don't you now need:

        depends on TYPEC || !TYPEC

>  	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 <dmitry.baryshkov@linaro.org>");
>  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)

You don't need that. You should not use ifdefs in .c files.

> +static int drm_typec_bus_event(struct notifier_block *nb,
> +			       unsigned long action, void *data)
> +{
> +	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

-- 
heikki