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

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Message-ID: <7cd2ab42-a6b4-41d2-bd3b-be043d69ffff@rock-chips.com>
Date: Thu, 23 Oct 2025 19:41:25 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.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>, 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 10/23/2025 7:36 PM, Heikki Krogerus wrote:
>> Thank you for your detailed explanation. I noticed that there is a
>> device_register() action in typec_register_altmode(), so we can just take
>> advantage of this.
>>
>> Another thing is that we need to distinguish between different devices in the
>> notifier callback, as
>> typec_register_altmode()/typec_register_partner()/typec_register_plug()/typec_register_cable()
>> may all register devices. Since the data passed in bus_notify() is struct
>> device *dev, I think we can distinguish them through `dev->type.name`? We may
>> already have such names, "typec_alternate_mode", "typec_partner", "typec_plug"
>> in class.c . And then extract these names as macros and put them in the typec
>> header file.
> You don't need to worry about that. Only partner altmodes are bind to
> the bus. The device you see in the notifier will always be an altmode.
>
> But in general, if you need to identify the device type, then
> you use the device type itself, not the name of the type. It would
> require that the device types are exported, but as said, you don't
> need to worry about that in this case.

Very insightful! I will try to do this in v8 :)


>
> thanks,
>
-- 
Best,
Chaoyi