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Message-ID: <aQTAdaIgjgTRSgxL@kuha.fi.intel.com>
Date: Fri, 31 Oct 2025 15:58:13 +0200
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Chaoyi Chen <kernel@...kyi.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Vinod Koul <vkoul@...nel.org>,
Kishon Vijay Abraham I <kishon@...nel.org>,
Heiko Stuebner <heiko@...ech.de>, Sandy Huang <hjc@...k-chips.com>,
Andy Yan <andy.yan@...k-chips.com>,
Yubing Zhang <yubing.zhang@...k-chips.com>,
Frank Wang <frank.wang@...k-chips.com>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Robert Foss <rfoss@...nel.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Amit Sunil Dhamne <amitsd@...gle.com>,
Chaoyi Chen <chaoyi.chen@...k-chips.com>,
Dragan Simic <dsimic@...jaro.org>, Johan Jonker <jbx6244@...il.com>,
Diederik de Haas <didi.debian@...ow.org>,
Peter Robinson <pbrobinson@...il.com>, linux-usb@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-phy@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
linux-rockchip@...ts.infradead.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v8 03/10] drm/bridge: Implement generic USB Type-C DP HPD
bridge
Wed, Oct 29, 2025 at 03:14:28PM +0800, Chaoyi Chen kirjoitti:
> From: Chaoyi Chen <chaoyi.chen@...k-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@...k-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@...aro.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
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