linux-kernel - Re: [PATCH v4 2/7] dt-bindings: phy: rockchip: rk3399-typec-phy: Support mode-switch

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Message-ID: <533d41bd-9293-4808-85f3-8fb6dc8bcda7@rock-chips.com>
Date: Tue, 23 Sep 2025 09:53:06 +0800
From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Chaoyi Chen <kernel@...kyi.com>
Cc: 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>,
 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>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 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 v4 2/7] dt-bindings: phy: rockchip: rk3399-typec-phy:
 Support mode-switch

Hi Dmitry,

On 9/23/2025 9:12 AM, Dmitry Baryshkov wrote:
> On Mon, Sep 22, 2025 at 09:20:34AM +0800, Chaoyi Chen wrote:
>> From: Chaoyi Chen <chaoyi.chen@...k-chips.com>
>>
>> The RK3399 SoC integrates two USB/DP combo PHYs, each of which
>> supports software-configurable pin mapping and DisplayPort lane
>> assignment. These capabilities enable the PHY itself to handle both
>> mode switching and orientation switching, based on the Type-C plug
>> orientation and USB PD negotiation results.
>>
>> While an external Type-C controller is still required to detect cable
>> attachment and report USB PD events, the actual mode and orientation
>> switching is performed internally by the PHY through software
>> configuration. This allows the PHY to act as a Type-C multiplexer for
>> both data role and DP altmode configuration.
>>
>> To reflect this hardware design, this patch introduces a new
>> "mode-switch" property for the dp-port node in the device tree bindings.
>> This property indicates that the connected PHY is capable of handling
>> Type-C mode switching itself.
>>
>> Signed-off-by: Chaoyi Chen <chaoyi.chen@...k-chips.com>
>>
>> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> ---
>>
>> Changes in v4:
>> - Remove "|" in description.
>>
>> Changes in v3:
>> - Add more descriptions to clarify the role of the PHY in switching.
>>
>> Changes in v2:
>> - Reuse dp-port/usb3-port in rk3399-typec-phy binding.
>>
>>   .../devicetree/bindings/phy/rockchip,rk3399-typec-phy.yaml  | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/phy/rockchip,rk3399-typec-phy.yaml b/Documentation/devicetree/bindings/phy/rockchip,rk3399-typec-phy.yaml
>> index 91c011f68cd0..83ebcde096ea 100644
>> --- a/Documentation/devicetree/bindings/phy/rockchip,rk3399-typec-phy.yaml
>> +++ b/Documentation/devicetree/bindings/phy/rockchip,rk3399-typec-phy.yaml
>> @@ -51,6 +51,12 @@ properties:
>>         '#phy-cells':
>>           const: 0
>>   
>> +      mode-switch:
> Having the mode-switch here is a bit strange. I think the whole PHY
> device should be an orientation-switch and mode-switch. Otherwise it
> feels weird to me.

I think this is a difference in practice. In the previous binding, there was already an orientation-switch under the usb-port. I trying to add both an orientation-switch and a mode-switch to the top-level device in v2. And Krzysztof reminded me that adding a mode-switch under the dp-port would be better, so I changed it to the current form :)



>
>> +        description:
>> +          Indicates the PHY can handle altmode switching. In this case,
>> +          requires an external USB Type-C controller to report USB PD message.
>> +        type: boolean
>> +
>>         port:
>>           $ref: /schemas/graph.yaml#/properties/port
>>           description: Connection to USB Type-C connector
>> -- 
>> 2.49.0
>>
-- 
Best,
Chaoyi