Subject: Re: [PATCH v4 1/2] dt-bindings: serial: Add rx-tx-swap to stm32-usart

From: Rob Herring <[email-masked]>
Date: Mon, 8 Mar 2021 12:20:40 -0700

On Tue, Mar 02, 2021 at 08:03:02PM +0100, Martin Devera wrote:
> Add new rx-tx-swap property to allow for RX & TX pin swapping.
> 
> Signed-off-by: Martin Devera <[email-masked]>
> ---
>  .../devicetree/bindings/serial/st,stm32-uart.yaml  | 32 +++++++++++++++-------
>  1 file changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml b/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
> index 8631678283f9..6eab2debebb5 100644
> --- a/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
> +++ b/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
> @@ -9,9 +9,6 @@ maintainers:
>  
>  title: STMicroelectronics STM32 USART bindings
>  
> -allOf:
> -  - $ref: rs485.yaml
> -
>  properties:
>    compatible:
>      enum:
> @@ -40,6 +37,10 @@ properties:
>  
>    uart-has-rtscts: true
>  
> +  rx-tx-swap:
> +    type: boolean
> +    maxItems: 1

Type is boolean, but 'maxItems' applies to arrays.

In any case, this is already defined in serial.yaml, so just 
'rx-tx-swap: true' here.

> +
>    dmas:
>      minItems: 1
>      maxItems: 2
> @@ -66,13 +67,24 @@ properties:
>    linux,rs485-enabled-at-boot-time: true
>    rs485-rx-during-tx: true
>  
> -if:
> -  required:
> -    - st,hw-flow-ctrl
> -then:
> -  properties:
> -    cts-gpios: false
> -    rts-gpios: false
> +allOf:

And add '- $ref: serial.yaml#' here.

> +  - $ref: rs485.yaml
> +  - if:
> +      required:
> +        - st,hw-flow-ctrl
> +    then:
> +      properties:
> +        cts-gpios: false
> +        rts-gpios: false
> +  - if:
> +      required:
> +        - rx-tx-swap
> +    then:
> +      properties:
> +        compatible:
> +          enum:
> +            - st,stm32f7-uart
> +            - st,stm32h7-uart

The normal pattern is the 'if' has compatible. You can put the other 
compatible strings in the if, and then 'then' is:

then:
  properties:
    rx-tx-swap: false

Rob

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