Message-ID: <p3kgqn3euumhysckh4yyqavqv5y6any5zcrgkrcg3j5a7z7cyw@lfpkla5p3put>
Date: Tue, 23 Sep 2025 13:45:39 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Chaoyi Chen <chaoyi.chen@...k-chips.com>
Cc: Chaoyi Chen <kernel@...kyi.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>,
        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

On Tue, Sep 23, 2025 at 03:17:20PM +0800, Chaoyi Chen wrote:
> 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@...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 :)
> > > > 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:

I see it now, I was probably looking at the different revision, sorry
about it.

> 
> 
> &tcphy0_dp {
>     port { ... };
> };
> 
> &tcphy0_usb3 {
>     port { ... };
> };
> 
> 
> Sorry, this looks a bit hacky. Do you have a better idea? Thank you.

No, it's fine from my POV now.

> 
> 
> > 
> > > 
> > > [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@...ts.infradead.org
> > > https://lists.infradead.org/mailman/listinfo/linux-phy
> 
> -- 
> Best,
> Chaoyi
> 

-- 
With best wishes
Dmitry

Powered by blists - more mailing lists