Date:   Tue, 28 Jun 2022 12:28:17 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Fabrice Gasnier <fabrice.gasnier@...s.st.com>, robh+dt@...nel.org,
        heikki.krogerus@...ux.intel.com, gregkh@...uxfoundation.org
Cc:     krzysztof.kozlowski+dt@...aro.org, devicetree@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        amelie.delaunay@...s.st.com, alexandre.torgue@...s.st.com
Subject: Re: [PATCH 1/4] dt-bindings: usb: typec: add bindings for stm32g0
 controller

On 27/06/2022 16:21, Fabrice Gasnier wrote:
> On 6/24/22 18:16, Krzysztof Kozlowski wrote:
>> On 24/06/2022 17:54, Fabrice Gasnier wrote:
>>> This patch adds DT schema documentation for the STM32G0 Type-C controller.
>>
>> No "This patch"
> 
> Hi Krzysztof,
> 
> ack,
> 
>>
>> https://elixir.bootlin.com/linux/v5.17.1/source/Documentation/process/submitting-patches.rst#L95
>>
>>> STM32G0 provides an integrated USB Type-C and power delivery interface.
>>> It can be programmed with a firmware to handle UCSI protocol over I2C
>>> interface. A GPIO is used as an interrupt line.
>>> It may be used as a wakeup source, so use optional "wakeup-source" and
>>> "power-domains" properties to support wakeup.
>>>
>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
>>> ---
>>>  .../bindings/usb/st,typec-stm32g0.yaml        | 83 +++++++++++++++++++
>>>  1 file changed, 83 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/usb/st,typec-stm32g0.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/usb/st,typec-stm32g0.yaml b/Documentation/devicetree/bindings/usb/st,typec-stm32g0.yaml
>>> new file mode 100644
>>> index 0000000000000..b2729bd015a1a
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/usb/st,typec-stm32g0.yaml
>>> @@ -0,0 +1,83 @@
>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: "http://devicetree.org/schemas/usb/st,typec-stm32g0.yaml#"
>>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>>
>> No quotes.
> 
> ack,
> 
>>
>>> +
>>> +title: STMicroelectronics STM32G0 Type-C controller bindings
>>
>> s/bindings//
> 
> ack,
> 
>>
>>> +
>>> +description: |
>>> +  The STM32G0 MCU can be programmed to control Type-C connector(s) through I2C
>>> +  typically using the UCSI protocol over I2C, with a dedicated alert
>>> +  (interrupt) pin.
>>> +
>>> +maintainers:
>>> +  - Fabrice Gasnier <fabrice.gasnier@...s.st.com>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    const: st,stm32g0-typec
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  interrupts:
>>> +    maxItems: 1
>>> +
>>> +  connector:
>>> +    type: object> +    allOf:
>>> +      - $ref: ../connector/usb-connector.yaml#
>>
>> Full path, so /schemas/connector/...
>>
>> unevaluatedProperties: false
> 
> ack,
> 
>>
>>> +
>>> +  firmware-name:
>>> +    description: |
>>> +      Should contain the name of the default firmware image
>>> +      file located on the firmware search path
>>> +
>>> +  wakeup-source: true
>>> +  power-domains: true
>>
>> maxItems
> 
> Do you mean maxItems regarding the "power-domains" property ?

Yes.

> This will depend on the user platform, where it's used as an I2C device.
> So I'm not sure this can / should be specified here.
> Could please you clarify ?

Then maybe this property is not valid here. Power domains usually are
used for blocks of a SoC, having common power source and power gating.
In your case it looks much more like a regulator supply.

> 
>>
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - interrupts
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/interrupt-controller/irq.h>
>>> +    i2c5 {
>>
>> Just "i2c"
> 
> ack,
> 
>>
>>> +      #address-cells = <1>;
>>> +      #size-cells = <0>;
>>> +
>>> +      stm32g0@53 {
>>
>> Generic node name describing class of the device.
> 
> 
> I wasn't aware of generic node name for an I2C device (not talking of
> the controller). I may have missed it.
> 
> Could you please clarify ?

The class of a device is not a I2C device. I2C is just a bus. For
example the generic name for Power Management IC connected over I2C
(quite common case) is "pmic".

For USB HCD controllers the generic name is "usb". For USB
ports/connectors this is "connector". So what is your hardware?
"interface" is a bit too unspecific to figure it out.

> 
>>
>>> +        compatible = "st,stm32g0-typec";
>>> +        reg = <0x53>;
>>> +        /* Alert pin on GPIO PE12 */
>>> +        interrupts = <12 IRQ_TYPE_EDGE_FALLING>;
>>> +        interrupt-parent = <&gpioe>;
>>> +
>>> +        /* Example with one type-C connector */
>>> +        connector {
>>> +          compatible = "usb-c-connector";
>>> +          label = "USB-C";
>>> +
>>> +          port {
>>
>> This does not look like proper schema of connector.yaml.
> 
> This refers to graph.yaml [1], where similar example is seen [2].
> 
> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/graph.yaml#L79
> 
> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/graph.yaml#L207

Just look at the usb-conector schema. It's different. You miss ports.
Maybe other properties as well.

> 
>     device-1 {
>         port {
>             device_1_output: endpoint {
>                 remote-endpoint = <&device_2_input>;
>             };
>         };
>     };
>     device-2 {
>         port {
>             device_2_input: endpoint {
>                 remote-endpoint = <&device_1_output>;
>             };
>         };
>     };
> 
> 
> Could you please clarify this point too ?
> 
>>
>>> +            con_usb_c_ep: endpoint {
>>> +              remote-endpoint = <&usbotg_hs_ep>;
>>> +            };
>>> +          };
>>> +        };
>>> +      };
>>> +    };
>>> +
>>> +    usbotg_hs {
>>
>> Generic node names, no underscores in node names.
> 
> ack, I guess you'd recommend "usb" here. I'll update it.

Yes, looks like usb.


Best regards,
Krzysztof

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