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

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Message-ID: <84f06c0f-3ec7-4a43-bba2-1979c3a07127@rock-chips.com>
Date: Fri, 5 Dec 2025 10:26:20 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 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>, 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 Heikki,

On 12/4/2025 9:40 PM, Heikki Krogerus wrote:
> Hi,
> 
> I don't know what's going on here - this series is the 12th?
> In any case, you need to fix this..
> 

It is 11th. Patch 1 was missing the Signed-off-by line, so I've resent
it. Sorry for the confusion.

>> 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));
>

Oh, it is. Will fix in v12. Thank you.

>> +	/*
>> +	 * 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,
> 

-- 
Best, 
Chaoyi