RE: [PATCH v6 1/6] dt-bindings: usb: add documentation for typec switch simple driver

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> -----Original Message-----
> From: Rob Herring <robh@xxxxxxxxxx>
> Sent: Tuesday, December 1, 2020 5:47 AM
> To: Jun Li <jun.li@xxxxxxx>
> Cc: heikki.krogerus@xxxxxxxxxxxxxxx; rafael@xxxxxxxxxx;
> gregkh@xxxxxxxxxxxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx;
> hdegoede@xxxxxxxxxx; lee.jones@xxxxxxxxxx;
> mika.westerberg@xxxxxxxxxxxxxxx; dmitry.torokhov@xxxxxxxxx;
> prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx;
> laurent.pinchart+renesas@xxxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; Peter Chen
> <peter.chen@xxxxxxx>
> Subject: Re: [PATCH v6 1/6] dt-bindings: usb: add documentation for typec
> switch simple driver
> 
> On Mon, Nov 23, 2020 at 10:01:31PM +0800, Li Jun wrote:
> > Some platforms need a simple driver to do some controls according to
> > typec orientation, this can be extended to be a generic driver with
> > compatible with "typec-orientation-switch".
> >
> > Signed-off-by: Li Jun <jun.li@xxxxxxx>
> > ---
> > changes for v6:
> > - Use general mux bindings for typec switch, one typec switch
> >   may have 1 or 2 GPIOs for channel selection, if 1 GPIO, only
> >   can be used to select cc1 or cc2; if 2 GPIOs, the second GPIO
> >   can be used to deselect both channels or keep normal operations.
> > - Add one more connection to usb controller.
> >
> > No changes for v5.
> >
> > changes on v4:
> > - Use compatible instead of bool property for switch matching.
> > - Change switch GPIO to be switch simple.
> > - Change the active channel selection GPIO to be optional.
> >
> > previous discussion:
> >
> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatch
> >
> work.ozlabs.org%2Fpatch%2F1054342%2F&amp;data=04%7C01%7Cjun.li%40nxp.c
> >
> om%7C4436142512ac45fef86f08d8957983c2%7C686ea1d3bc2b4c6fa92cd99c5c3016
> >
> 35%7C0%7C1%7C637423696442152522%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLj
> >
> AwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=
> > JCV9OtFkfLv4bH2LIxfnk0lVIO6j830%2F%2Bx2OMOi%2Fs6o%3D&amp;reserved=0
> >
> >  .../bindings/usb/typec-switch-simple.yaml          | 122
> +++++++++++++++++++++
> >  1 file changed, 122 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/usb/typec-switch-simple.yaml
> > b/Documentation/devicetree/bindings/usb/typec-switch-simple.yaml
> > new file mode 100644
> > index 0000000..030ade5
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/typec-switch-simple.yaml
> > @@ -0,0 +1,122 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > +---
> > +$id:
> >
> +https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevi
> >
> +cetree.org%2Fschemas%2Fusb%2Ftypec-switch-simple.yaml%23&amp;data=04%
> >
> +7C01%7Cjun.li%40nxp.com%7C4436142512ac45fef86f08d8957983c2%7C686ea1d3
> >
> +bc2b4c6fa92cd99c5c301635%7C0%7C1%7C637423696442152522%7CUnknown%7CTWF
> >
> +pbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6
> >
> +Mn0%3D%7C3000&amp;sdata=vSLcoGYWCgwpsi4LWbKo2VTyCVgN%2BA7zjHfE8QCS4rg
> > +%3D&amp;reserved=0
> > +$schema:
> >
> +https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevi
> >
> +cetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=04%7C01%7Cjun.li%40
> >
> +nxp.com%7C4436142512ac45fef86f08d8957983c2%7C686ea1d3bc2b4c6fa92cd99c
> >
> +5c301635%7C0%7C1%7C637423696442152522%7CUnknown%7CTWFpbGZsb3d8eyJWIjo
> >
> +iMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&am
> >
> +p;sdata=0fd3wjAtKwLCQAY3NG2Be4qNA9FiFhtO0HIZmCK7AQs%3D&amp;reserved=0
> > +
> > +title: Typec Orientation Switch Simple Solution Bindings
> > +
> > +maintainers:
> > +  - Li Jun <jun.li@xxxxxxx>
> > +
> > +description: |-
> > +  USB SuperSpeed (SS) lanes routing to which side of typec connector
> > +is
> > +  decided by orientation, this maybe achieved by some simple control
> > +like
> > +  GPIO toggle.
> > +
> > +properties:
> > +  compatible:
> > +    const: typec-orientation-switch
> > +
> > +  '#mux-control-cells':
> > +    const: 0
> 
> Who is the mux-control consumer?

Typec(controller)

       ptn5110: tcpc@50 {
                compatible = "nxp,ptn5110";
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_typec>;
                reg = <0x50>;
                interrupt-parent = <&gpio4>;
                interrupts = <19 8>;
                mux-controls = <&typec_switch>;
                mux-control-names = "mux-typec-switch";

                usb_con: connector {
                        compatible = "usb-c-connector";
                        ... ...
                        ports {
                                #address-cells = <1>;
                                #size-cells = <0>;

                                port@1 {
                                        reg = <1>;
                                        typec_con_ss: endpoint {
                                                remote-endpoint = <&usb3_orien_sel>;
                                        };
                                };
                        };
                };
        };

> 
> > +
> > +  switch-gpios:
> > +    description: |
> > +      GPIO specifiers to select the target channel of mux.
> > +      The first GPIO is for cc1 and cc2 selection, the GPIO flag use
> > +      GPIO_ACTIVE_HIGH if GPIO physical state high is for cc1; or use
> > +      GPIO_ACTIVE_LOW if GPIO physical state low is for cc1.
> > +      The second gpio is to deselect any channles by places all channels
> > +      in high-impedance state to reduce current consumption, the gpio
> flag
> > +      use GPIO_ACTIVE_HIGH if GPIO physical state high is for
> > +      high-impedance state (so low for normal operations); or Use
> > +      GPIO_ACTIVE_LOW if GPIO physical state low is for high-impedance
> > +      state(so high for normal operations).
> > +    minItems: 1
> > +    maxItems: 2
> > +
> > +  idle-state:
> > +    description: -|
> > +      For TYPEC_ORIENTATION_NONE by deselect both channels if supported.
> > +    const: 2
> > +
> > +  # Standard properties described in
> > +  # Documentation/devicetree/bindings/mux/mux-controller.txt
> > +
> > +  port:
> > +    type: object
> > +    additionalProperties: false
> > +    description: -|
> > +      Connection to the remote endpoint using OF graph bindings that model
> > +      SS data bus to typec connector.
> > +
> > +    properties:
> > +      '#address-cells':
> > +        const: 1
> > +
> > +      '#size-cells':
> > +        const: 0
> > +
> > +      endpoint@0:
> > +        type: object
> > +        description: Endpoint connected to typec connector.
> > +        additionalProperties: false
> > +
> > +        properties:
> > +          reg:
> > +            const: 0
> > +          remote-endpoint: true
> > +
> > +        required:
> > +          - remote-endpoint
> > +
> > +      endpoint@1:
> > +        type: object
> > +        description: Endpoint connected to usb controller.
> > +        additionalProperties: false
> > +
> > +        properties:
> > +          reg:
> > +            const: 1
> > +          remote-endpoint: true
> > +
> > +        required:
> > +          - remote-endpoint
> > +
> > +    required:
> > +      - endpoint@0
> > +
> > +required:
> > +  - compatible
> > +  - port
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    typec_switch: mux-controller {
> > +        compatible = "typec-orientation-switch";
> > +        #mux-control-cells = <0>;
> > +        pinctrl-names = "default";
> > +        pinctrl-0 = <&pinctrl_ss_sel>;
> > +        switch-gpios = <&gpio3 15 GPIO_ACTIVE_HIGH>,
> > +                       <&gpio2 20 GPIO_ACTIVE_HIGH>;
> > +        idle-state = <2>;
> > +
> > +        port {
> > +                #address-cells = <1>;
> > +                #size-cells = <0>;
> > +
> > +                usb3_orien_sel: endpoint@0 {
> > +                        reg = <0>;
> > +                        remote-endpoint = <&typec_con_ss>;
> > +                };
> > +
> > +                usb3_con_data: endpoint@1 {
> > +                        reg = <1>;
> > +                        remote-endpoint = <&dwc3_0>;
> > +                };
> > +        };
> 
> This still seems unnecessarily complicated. What I had in mind is just
> something like this:
> 
> mux: mux-controller {
>   compatible = "gpio-mux";
>   #mux-control-cells = <0>;
>   mux-gpios = <&gpio3 15 GPIO_ACTIVE_HIGH>,
>               <&gpio2 20 GPIO_ACTIVE_HIGH>;
>   idle-state = <2>;
> };
> 
> connector {
>   compatible = "usb-c-connector";
>   mux-controls = <&mux>;
>   ...
> };
> 
> Then you aren't re-implementing the gpio-mux driver.
> 
> This should work for *any* mux implementation as long as the mux states always
> have the same meanings from the perspective of the connector.
>
> Of course, I have little visibility into the possible h/w implementations
> for Type-C and maybe this isn't sufficient. So input from Type-C experts
> would be helpful.

>From h/w point view, this can work if only consider my(GPIO) case.
But I still need register a typec switch in provider side to make it
under the unified typec switch interface:

  7 struct typec_switch {
  6         struct device dev;
  5         typec_switch_set_fn_t set;
  4         struct mux_control *mux_ctrl;
  3 };

typec_switch->dev.parent = mux_chip->dev;

So either I put the typec switch creation in exiting mux-gpio driver; or
I create a new typec switch driver with gpio mux code duplication.

If I go directly with mux control w/o(out of) typec_switch, then I don't
need any driver change as you expect, but I guess this is not preferred,
@Heikki, any comments?

Thanks
Li Jun

> 
> Rob




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