From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-m1973194.qiye.163.com (mail-m1973194.qiye.163.com [220.197.31.94]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A640E351C3D; Fri, 29 May 2026 01:53:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.94 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780019635; cv=none; b=F8jQt4SHS2m/JuGpm152AwR7JmgbOgzOwh2p2sl3rXhdsXlA9ZO8QaxALygF8bR3NOOAGgFCNEpYCBwj5cSB+az9gLm7NWLW6FTYv2dehXZNGtmI6u5c79IrlCwfFUMMhwoDsceCCOVN66niol2zpn3YLUjeoALKm2XltbZdOGI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780019635; c=relaxed/simple; bh=JuI14DrowmBFfoTf7bMpo7hwTLadRarUIO9k/1D0SNY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=dd/JPAwylp7fEtoUjriqRV59AP5C4zzsPFhRkbH/kGrv+cmX/wsVkxrPA2N+Gwt4+C5IEU45zcfXUavTzraNvy658lytSjEcXM7hGmQ7zUlDCThBFdqJT3ei77S8E9tzxbjjE71mctSr1/leBQOYSY+E3A6c91s8BOnzNzePG3M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rock-chips.com; spf=pass smtp.mailfrom=rock-chips.com; dkim=pass (1024-bit key) header.d=rock-chips.com header.i=@rock-chips.com header.b=XH3HAMkJ; arc=none smtp.client-ip=220.197.31.94 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=rock-chips.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rock-chips.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=rock-chips.com header.i=@rock-chips.com header.b="XH3HAMkJ" Received: from [172.16.12.90] (unknown [61.154.14.86]) by smtp.qiye.163.com (Hmail) with ESMTP id 403fe69fb; Fri, 29 May 2026 09:18:05 +0800 (GMT+08:00) Message-ID: <162da16e-6fec-4d47-ba67-46ec2ffa8e2f@rock-chips.com> Date: Fri, 29 May 2026 09:18:03 +0800 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v15 1/9] drm/bridge: Implement generic USB Type-C DP HPD bridge To: Nicolas Frattaroli Cc: 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, 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, Chaoyi Chen References: <20260304094152.92-1-kernel@airkyi.com> <20260304094152.92-2-kernel@airkyi.com> Content-Language: en-US From: Chaoyi Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-HM-Tid: 0a9e714f575603a7kunm02f79646c276f X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFITzdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVlDTkkYVkJCS01DQ0pLQx1KTVYVFA kWGhdVEwETFhoSFyQUDg9ZV1kYEgtZQVlNSlVKTk9VSk9VQ01ZV1kWGg8SFR0UWUFZT0tIVUpLSE pKQk1VSktLVUpCWQY+ DKIM-Signature: a=rsa-sha256; b=XH3HAMkJS0xVohcQuMdKTriE7Bx8yFw6eb42zoSKsvGfn7hX654CyUvDAI5X7TDt3QLQKsY0JYgFk82I6qcr7FwY1sB0NglC9697BPY9uHlC0kePlaHxXstQmxJq3qRRm5aETC3C2H7j2/19/UHeGZCfVTUs9fJAGvk+bTsSZpI=; c=relaxed/relaxed; s=default; d=rock-chips.com; v=1; bh=IFhWtiTca4KN7jNJbQ39dVsqplJfAuEyUAlnwh0AXXA=; h=date:mime-version:subject:message-id:from; Hello Nicolas, On 5/28/2026 11:37 PM, Nicolas Frattaroli wrote: > 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. > Oh! I hadn't noticed that. Thank you for your legal advice. >> +#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. > Yep. Will fix in v2. >> + 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. > Will fix in v2. >> + >> +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 > > > -- Best, Chaoyi