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

[Chaoyi Chen <chaoyi.chen@rock-chips.com>]

On 9/23/2025 12:51 PM, Dmitry Baryshkov wrote:

> On Tue, Sep 23, 2025 at 11:40:33AM +0800, Chaoyi Chen wrote:
>> On 9/23/2025 11:17 AM, Dmitry Baryshkov wrote:
>>
>>> On Tue, Sep 23, 2025 at 09:53:06AM +0800, Chaoyi Chen wrote:
>>>> 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@rock-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@rock-chips.com>
>>>>>>
>>>>>> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.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 :)
>>> I couldn't find the comment on lore. Could you please point it out?
>> Sorry, it is v1. I added an orientation-switch and a mode-switch in the top-level PHY [0]. Comment is here: [1]
> My interpretation of [1] doesn't quite match yours. It doesn't say
> anything about moving mode-switch to dp-port. It basically pointed out
> that you already have two ports.

Yes, I think this can be easily changed, as long as the issue you mentioned below is resolved.


>
> Also, I'm not sure how the current construction works: you register
> switch and mux for the dev_fwnode(tcphy->dev), however the lookfup
> functions should be looking for a device corresponding to the port OF
> node (which doesn't exist).

In v1, that is fwnode = dev_fwnode(tcphy->dev) .  And dt like is:


&tcphy {
     port {
         tcphy0_orientation_switch: endpoint@0 { ... };
         tcphy_dp_altmode_switch: endpoint@1 { ... };
     };
};


Since the binding already includes a "usb3-port" and a "dp-port", it can not add another new port.

So after v1, that is fwnode = device_get_named_child_node(tcphy->dev, "usb3-port") . And dt like this:


&tcphy0_dp {
     port { ... };
};

&tcphy0_usb3 {
     port { ... };
};


Sorry, this looks a bit hacky. Do you have a better idea? Thank you.


>
>>
>> [0] https://lore.kernel.org/all/20250715112456.101-4-kernel@airkyi.com/
>>
>> [1] https://lore.kernel.org/all/4dfed94c-665d-4e04-b527-ddd34fd3db8f@kernel.org/
>>
>>
>>
>>>>
>>>>>> +        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
>>>>
>> -- 
>> Best,
>> Chaoyi
>>
>>
>> -- 
>> linux-phy mailing list
>> linux-phy@lists.infradead.org
>> https://lists.infradead.org/mailman/listinfo/linux-phy

-- 
Best,
Chaoyi