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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=1780351737; s=zohomail; d=collabora.com; i=sebastian.reichel@collabora.com; h=Date:Date:From:From:To:To:Cc:Cc:Subject:Subject:Message-ID:References:MIME-Version:Content-Type:In-Reply-To:Message-Id:Reply-To; bh=1lK1yNZdrKT8RuPFT6vih0wWSf1jo44LoNBqX+KfL0M=; b=BUIQ3fbngH6E2GT5G7rpUSBewxAJyxIl+lR3yFYwvtS2tqoPkRt7+/Muq5CFSNaL mV6NLFOKmwKjS6jyoO/Wjw5dePkldz5YHfYGq0wbVLSyK6vPS9caCalpe7Tp2HCHLWC sX1JY7n/mW01G2j7r4weTdsWLFO2IWm3ZmbWPssc= Received: by mx.zohomail.com with SMTPS id 1780351733835755.6229336935343; Mon, 1 Jun 2026 15:08:53 -0700 (PDT) Received: by venus (Postfix, from userid 1000) id D5550183854; Tue, 02 Jun 2026 00:08:46 +0200 (CEST) Date: Tue, 2 Jun 2026 00:08:46 +0200 From: Sebastian Reichel To: Chaoyi Chen Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Sandy Huang , Heiko =?utf-8?Q?St=C3=BCbner?= , Andy Yan , Vinod Koul , Heikki Krogerus , Dmitry Baryshkov , Luca Ceresoli , 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, Chaoyi Chen Subject: Re: [PATCH 1/5] drm/bridge: Implement generic USB Type-C DP HPD bridge Message-ID: References: <20260521032854.103-1-kernel@airkyi.com> <20260521032854.103-2-kernel@airkyi.com> MIME-Version: 1.0 In-Reply-To: <20260521032854.103-2-kernel@airkyi.com> X-Zoho-Virus-Status: 1 X-Zoho-AV-Stamp: zmail-av-0.2.2.1.5.2/280.325.56 X-ZohoMailClient: External X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260601_150931_576774_A2AD378D X-CRM114-Status: GOOD ( 34.26 ) 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="===============2926379647262307279==" Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org --===============2926379647262307279== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="2wjtyeyqji5ix4fa" Content-Disposition: inline --2wjtyeyqji5ix4fa Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH 1/5] drm/bridge: Implement generic USB Type-C DP HPD bridge MIME-Version: 1.0 Hi, On Thu, May 21, 2026 at 11:28:50AM +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 > --- > drivers/gpu/drm/bridge/Kconfig | 10 ++++ > drivers/gpu/drm/bridge/Makefile | 1 + > .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c | 49 +++++++++++++++++++ Doesn't this require removing the manual registration of the HPD auxillary bridge in the USB-C controller drivers to avoid that two bridges are registered for them? > 3 files changed, 60 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 c3209b0f4678..d92e93875793 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 beab5b695a6e..c4761526ba0a 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..d915e0fb0668 > --- /dev/null > +++ b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c > @@ -0,0 +1,49 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +#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) > + 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 =3D=3D USB_TYPEC_DP_S= ID) > + drm_dp_hpd_bridge_register(alt->dev.parent->parent, > + to_of_node(alt->dev.parent->fwnode)); IIUIC this is called when the USB-C controller spawns a sub-device for the DP AltMode and then registers a HPD bridge to the USB-C controller itself. Wouldn't that register new HPD bridges on every USB-C replug? Also doesn't this result in the bridge not being registered when nothing is plugged and thus the DRM pipeline not being able to bind properly? Greetings, -- Sebastian > + > +done: > + 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_DESCRIPTION("DRM TYPEC DP HPD BRIDGE"); > +MODULE_LICENSE("GPL"); > --=20 > 2.53.0 >=20 >=20 --2wjtyeyqji5ix4fa Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEE72YNB0Y/i3JqeVQT2O7X88g7+poFAmoeAusACgkQ2O7X88g7 +poFDhAAqmoRFuBnWXN9ThmBhdcTbKmP9xRiRbmFvKqyJCJGzQ3m9vJWXeRgnm2p xp0Pd6zOCm4m4snw4PElFYmAJACJZbKD19oPGRUy7ClzIHqyQUmh/DweeHexRcwb iS7XC9qxSrCmkWu2/CVYnIVDb+YeC7/aMwjMG5nn6PL3i0ftBqiMGM2TFbka3O+1 THzO03GrjEl3f2mNJm2HYI//Lsl27+WXebGweEhyGtZIoI+BGi3uCMLq7afmeKc+ BhTXSJAjHQDo76RglJLBiOi1PfeLQT8SLxu6cfqTIrjVnBoy7iPTtopTpuQK5a8g nVh8C7wuSwHhO0FAp2kt6JeFYTzLRQj6YCdMdzIS8fw9vc9dSKgwFhTk6wDbDzds Z6qmigIPYvawBo3cWy20RHQynxXchqaKbSqT9IJ3QxdHgGiNdPc5AzrS3V/Oyi/s q4QWtaqoLN1qCTGVNOnqJ+1vQhzBuLZCZJt/g8nlJMYSVUe0RYGXRUjOgK9f1B97 Vc1myj5dNB1u5EwcRhcDopxmw6S95GqAPZydo9yduYUIj2Uu5adlFGDZiaJMoZvz w/51Wmp/n+azkiSyBhjPLr9ieZD/WKuUpbAwzeLv/B9cL+L2i3n1PtAwwj/W3Tgx VP8/olbfezC3hFV6Wwzap+LPLW91JARUpjYwZuptpDcuDDfsVho= =0qDd -----END PGP SIGNATURE----- --2wjtyeyqji5ix4fa-- --===============2926379647262307279== 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 --===============2926379647262307279==--