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mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=sebastian.reichel@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1784308777; s=zohomail; d=collabora.com; i=sebastian.reichel@collabora.com; h=Date:Date:From:From:To:To:Cc:Cc:Subject:Subject:Message-ID:MIME-Version:Content-Type:In-Reply-To:Message-Id:Reply-To; bh=ogRVHXmQ7ZTJHboM5CyugXRM1/jtS4o3Av3SvfnT0jM=; b=Kt6hXTUPPH6CFVs5HGy+sK42o+r4NCkzV6Q9KDzVFjAQW/qbb1HX75xBc8USxQgx RexIGKLGYtbvejBVzCeDDvxU/hevu/BjXDIhBq48yYc0cn0fZjxN7Wjiv0+aYjBEVgt YAda0f9SiK99bk32KBOvI3qSvslKA4kIskVrC6RI= Received: by mx.zohomail.com with SMTPS id 178430877525932.612933366387324; Fri, 17 Jul 2026 10:19:35 -0700 (PDT) Received: by venus (Postfix, from userid 1000) id 1F724181CD9; Fri, 17 Jul 2026 19:19:29 +0200 (CEST) Date: Fri, 17 Jul 2026 19:19:29 +0200 From: Sebastian Reichel To: Chaoyi Chen Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Sandy Huang , Heiko =?utf-8?Q?St=C3=BCbner?= , Andy Yan , Vinod Koul , Chaoyi Chen , Nicolas Frattaroli , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-phy@lists.infradead.org Subject: Re: [PATCH v3 1/5] drm/bridge: Implement generic USB Type-C DP HPD bridge Message-ID: References: <20260717072323.96-1-kernel@airkyi.com> <20260717072323.96-2-kernel@airkyi.com> MIME-Version: 1.0 In-Reply-To: <20260717072323.96-2-kernel@airkyi.com> X-Zoho-Virus-Status: 1 X-Zoho-AV-Stamp: zmail-av-0.2.10.1.5.2/284.287.57 X-ZohoMailClient: External X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260717_102022_196158_F8190B22 X-CRM114-Status: GOOD ( 34.79 ) X-BeenThere: linux-phy@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux Phy Mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============5321863631487179391==" Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org --===============5321863631487179391== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="jbdw5cv6ljemwd7w" Content-Disposition: inline --jbdw5cv6ljemwd7w Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH v3 1/5] drm/bridge: Implement generic USB Type-C DP HPD bridge MIME-Version: 1.0 Hello, On Fri, Jul 17, 2026 at 03:23:19PM +0800, Chaoyi Chen wrote: > From: Chaoyi Chen >=20 > 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. >=20 > To describe the relationship between the DP controller and the Type-C > port device, we usually using drm_bridge to build a bridge chain. >=20 > 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. >=20 > 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. >=20 > 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. >=20 > Signed-off-by: Chaoyi Chen > Reviewed-by: Heikki Krogerus > Reviewed-by: Nicolas Frattaroli > --- Reviewed-by: Sebastian Reichel Tested-by: Sebastian Reichel # ArmSom Sig= e5 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 =2E.. 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 =2E.. 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) >=20 > Changes in v2: > - Add copyright text. > - Remove useless goto. >=20 > --- > 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 >=20 > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kcon= fig > 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. > =20 > +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 > =20 > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Mak= efile > 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-$(CONFIG_DRM_AUX_BRIDGE) +=3D aux-bridge.o > obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) +=3D aux-hpd-bridge.o > +obj-$(CONFIG_DRM_AUX_HPD_TYPEC_BRIDGE) +=3D aux-hpd-typec-dp-bridge.o > obj-$(CONFIG_DRM_CHIPONE_ICN6211) +=3D chipone-icn6211.o > obj-$(CONFIG_DRM_CHRONTEL_CH7033) +=3D chrontel-ch7033.o > obj-$(CONFIG_DRM_CROS_EC_ANX7688) +=3D cros-ec-anx7688.o > diff --git a/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c b/drivers/g= pu/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 > + */ > +#include > +#include > +#include > + > +#include > + > +static int drm_typec_bus_event(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct device *dev =3D (struct device *)data; > + struct typec_altmode *alt =3D to_typec_altmode(dev); > + > + if (action !=3D 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 =3D=3D USB_TYPEC_DP_S= ID) > + 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 =3D { > + .notifier_call =3D 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 "); > +MODULE_DESCRIPTION("DRM TYPEC DP HPD BRIDGE"); > +MODULE_LICENSE("GPL"); > --=20 > 2.53.0 >=20 --jbdw5cv6ljemwd7w Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE72YNB0Y/i3JqeVQT2O7X88g7+poFAmpaZBQACgkQ2O7X88g7 +po4qA/+IBHGDueFgcm82WUb8KlcPZXHjJIodD4gCNh2En34PfHdv2tgAZk8FNoa 130uQsjBUVejRARr4hgsqrKrisG/t/JfzHqg1DZpeok3j+sqCCDjuOYg3HBRrpjx WgTnxT7RWYqUjKE1bNX957wGBqggHx53///8/q2wwk4lCg99GEkoEqbbCgL4nQtb qwaQxOzI012LR46Q1c7lfSYYtjIAJEP2ojNbQUyUSuP58zZs2LsgdR0x8QVHx8h+ PdwS92uTNQ5iMEWZh/jkB3xUaS3Rr9avZSwdaRgL0nGYnsuC5gBDBuVQtgFztnJl gK80/W5U61uXnj4IY1i61+V5jwNvBbqnSG0VXaN85zbMEhH6IwWPFb4SFm2NduwN ba93B+wOyFXoTZ+xPy1PLjQ3jwaHG91tw2gQLurisvb9+eAbGdFKbG2t6pkvCuD2 LcwFHTSTD/gpsWMRiz4Lbz0I49jSRgW5x0wB4HOsOMDrFVDR8+MqNKMKHdErPqRp ZUeligeDaPclFpvT/ea7ChBipXN6/T6DvnwWe+Rsrn663mE3Y+GgOHiCYyfZZcRc SZk1gwoEskqaR6tguKoHT5hJwH30MVTmQDLL5I8AFij9LVl7MehM+DPjS+kRTE35 FnmtXnvKOa19o/QDH4N/zq1C+ayxbN+IQKCaJ2g3irXGVpl4q38= =wii+ -----END PGP SIGNATURE----- --jbdw5cv6ljemwd7w-- --===============5321863631487179391== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy --===============5321863631487179391==--