linux-kernel - Re: [PATCH v7 1/9] usb: typec: Add notifier functions

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Message-ID: <4fddba9a-b073-4bca-bd13-64a415f4bc47@rock-chips.com>
Date: Fri, 24 Oct 2025 15:59:50 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc: Chaoyi Chen <kernel@...kyi.com>,
 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>, 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 1/9] usb: typec: Add notifier functions

Hi Heikki,

On 10/24/2025 3:43 PM, Heikki Krogerus wrote:
>> I noticed the following statement in typec_register_altmode():
>>
>> ```
>>
>>      /* The partners are bind to drivers */
>>      if (is_typec_partner(parent))
>>          alt->adev.dev.bus = &typec_bus;
>>
>> ```
>>
>> If the condition is not met, the bus will not be set, which means bus_notify()
>> won't be able to take effect. Did I miss something?
> Right, that would be the condition that I was talking about. Only
> partner altmodes are used in the bus.
>
> Hold on! Do you need the port altmode instead of the partner altmode?
> If that's the case, then we can't use the bus notifier. So we'll need
> the separate notifier chain after all.

Yes, we need port altmode.  The partner altmode device appears too late for DRM device, as it only shows up after the corresponding DP device is inserted.


>
> Let me take a closer look at patch 2/9. Sorry about the hassle.
>
-- 
Best,
Chaoyi