linux-kernel - Re: [RESEND PATCH v11 03/11] drm/bridge: Implement generic USB Type-C DP HPD bridge

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Message-ID: <aTGPaJmwd7uHfrnV@kuha>
Date: Thu, 4 Dec 2025 15:40:56 +0200
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>,
	Peter Chen <hzpeterchen@...il.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.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: [RESEND PATCH v11 03/11] drm/bridge: Implement generic USB
 Type-C DP HPD bridge

Hi,

I don't know what's going on here - this series is the 12th?
In any case, you need to fix this..

> 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..94be3d5f69e9
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +#include <linux/of.h>
> +#include <linux/usb/typec_altmode.h>
> +#include <linux/usb/typec_dp.h>
> +
> +#include <drm/bridge/aux-bridge.h>
> +
> +static int drm_typec_bus_event(struct notifier_block *nb,
> +			       unsigned long action, void *data)
> +{
> +	struct device *dev = (struct device *)data;
> +	struct typec_altmode *alt = to_typec_altmode(dev);
> +
> +	if (action != BUS_NOTIFY_ADD_DEVICE)
> +		goto done;
> +
> +	if (is_typec_partner_altmode(&alt->dev) || alt->svid != USB_TYPEC_DP_SID)
> +		goto done;

That's still not enough because of the plug altmodes. You need to
check that it's a port altmode:

        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));

> +	/*
> +	 * 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));
> +
> +done:
> +	return NOTIFY_OK;
> +}
> +
> +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");

thanks,

-- 
heikki