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mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=nicolas.frattaroli@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1779982643; s=zohomail; d=collabora.com; i=nicolas.frattaroli@collabora.com; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Content-Type:Message-Id:Reply-To; bh=hx6IngChPzu8wVFfFvPOU9rvJKQ/Ut7ytcKKn5x2rGo=; b=Gv+tohvhN+Q91PScXFZSx7Yqg3dd2TPLxKiFsIK9A7Qx4du0tJ3PLa19oqdrMlG/ J8zxhIsPW3tBY5qn1bHUw5Iot5mzRvPkRA3IR4fnluUtb+DvGo6Z/SJdcHgtH3hrQWK LtrRp0QQyYArHz1vZJNxzlzeTk13hX0E1izuf6BM= Received: by mx.zohomail.com with SMTPS id 1779982641704569.2331869375547; Thu, 28 May 2026 08:37:21 -0700 (PDT) From: Nicolas Frattaroli To: Heikki Krogerus , Greg Kroah-Hartman , Dmitry Baryshkov , Peter Chen , Luca Ceresoli , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Vinod Koul , Kishon Vijay Abraham I , Heiko Stuebner , Sandy Huang , Andy Yan , Yubing Zhang , Frank Wang , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Amit Sunil Dhamne , Dragan Simic , Johan Jonker , Diederik de Haas , Peter Robinson , Hugh Cole-Baker , dri-devel@lists.freedesktop.org, Chaoyi Chen Cc: linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-phy@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, dri-devel@lists.freedesktop.org, Chaoyi Chen Subject: Re: [PATCH v15 1/9] drm/bridge: Implement generic USB Type-C DP HPD bridge Date: Thu, 28 May 2026 17:37:10 +0200 Message-ID: In-Reply-To: <20260304094152.92-2-kernel@airkyi.com> References: <20260304094152.92-1-kernel@airkyi.com> <20260304094152.92-2-kernel@airkyi.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260528_083808_987830_893C10A8 X-CRM114-Status: GOOD ( 36.83 ) 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: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org On Wednesday, 4 March 2026 10:41:44 Central European Summer Time Chaoyi Chen wrote: > From: Chaoyi Chen > > 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. > > To describe the relationship between the DP controller and the Type-C > port device, we usually using drm_bridge to build a bridge chain. > > 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. > > 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. > > 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. > > Signed-off-by: Chaoyi Chen > Reviewed-by: Heikki Krogerus > --- > > (no changes since v14) > > Changes in v13: > - Only register drm dp hpd bridge for typec port altmode device. > > (no changes since v12) > > Changes in v11: > - Switch to using typec bus notifiers. > > (no changes since v10) > > Changes in v9: > - Remove the exposed DRM_AUX_HPD_BRIDGE option, and select > DRM_AUX_HPD_TYPEC_BRIDGE when it is available. > - Add more commit comment about problem background. > > Changes in v8: > - Merge generic DP HPD bridge into one module. > --- > > drivers/gpu/drm/bridge/Kconfig | 10 ++++ > drivers/gpu/drm/bridge/Makefile | 1 + > .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c | 49 +++++++++++++++++++ > 3 files changed, 60 insertions(+) > 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..559487aa09a9 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. > > +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 > > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile > index c7dc03182e59..a3a0393d2e72 100644 > --- a/drivers/gpu/drm/bridge/Makefile > +++ b/drivers/gpu/drm/bridge/Makefile > @@ -1,6 +1,7 @@ > # SPDX-License-Identifier: GPL-2.0 > obj-$(CONFIG_DRM_AUX_BRIDGE) += aux-bridge.o > obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) += aux-hpd-bridge.o > +obj-$(CONFIG_DRM_AUX_HPD_TYPEC_BRIDGE) += aux-hpd-typec-dp-bridge.o > obj-$(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-typec-dp-bridge.c b/drivers/gpu/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+ Having a copyright statement added here is likely required. Something like /* * Copyright (C) 2026 Rockchip Electronics Co., Ltd. * * Author: Chaoyi Chen */ will suffice. While I hope it's never relevant for a driver this small, explicit copyright statements in this form have a legal effect in some jurisdictions like the US, where by law it automatically dismisses the defense that the copyright holder wasn't known. > +#include > +#include > +#include > + > +#include > + > +static int drm_typec_bus_event(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + struct device *dev = (struct device *)data; Small nitpick: The explicit (struct device *) cast of data isn't needed here. Just struct device *dev = data; will work fine. The benefit is that if the type of "data" ever changes (e.g. from void *data to const void *data) then we're not silencing a warning/error through an explicit cast. > + struct typec_altmode *alt = to_typec_altmode(dev); > + > + if (action != 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 == USB_TYPEC_DP_SID) > + drm_dp_hpd_bridge_register(alt->dev.parent->parent, > + to_of_node(alt->dev.parent->fwnode)); > + > +done: > + return NOTIFY_OK; > +} Nitpicking: the "done" label and "goto done" here is redundant. You could remove the label and replace the goto with another "return NOTIFY_OK;". There's no functional change here though. > + > +static struct notifier_block drm_typec_event_nb = { > + .notifier_call = 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"); > Feel free to add yourself as MODULE_AUTHOR here. :) With those things changed: Reviewed-by: Nicolas Frattaroli Kind regards, Nicolas Frattaroli -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy