linux-kernel - Re: [PATCH v7 2/9] drm/bridge: Implement generic USB Type-C DP HPD bridge

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Message-ID: <aPsyPTTq3bD2mo87@kuha.fi.intel.com>
Date: Fri, 24 Oct 2025 11:01:01 +0300
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Chaoyi Chen <kernel@...kyi.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	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>,
	Chaoyi Chen <chaoyi.chen@...k-chips.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 v7 2/9] drm/bridge: Implement generic USB Type-C DP HPD
 bridge

On Thu, Oct 23, 2025 at 11:30:02AM +0800, Chaoyi Chen wrote:
> +static int drm_typec_bus_event(struct notifier_block *nb,
> +			       unsigned long action, void *data)
> +{
> +	struct typec_altmode *alt = (struct typec_altmode *)data;
> +
> +	if (action != TYPEC_ALTMODE_REGISTERED)
> +		goto done;
> +
> +	if (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));

Okay, this explains it. So you do need the port altmode.

So you'll need to export the device types and check that the parent of
the altmode is the port instead of partner.

        if (!is_typec_port(alt->dev.parent) || alt->svid != USB_TYPEC_DP_SID)
                return NOTIFY_DONE;

I think we might as well export all the types while at it. Check the
attachment.

thanks,

-- 
heikki

View attachment "export_typec_dev_types.diff" of type "text/plain" (3036 bytes)