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Message-ID: <eca9d5bd-23bd-4c1d-b2f2-c0c32f14177f@rock-chips.com>
Date: Mon, 3 Nov 2025 14:24:12 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
Chaoyi Chen <kernel@...kyi.com>
Cc: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
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>, 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
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 <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.
> 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 <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"
> 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 <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)
>> +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
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