linux-kernel - Re: [PATCH v3 2/3] dt-bindings: phy: ti,phy-j721e-wiz: Add Type-C dir GPIO

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Date:   Fri, 25 Oct 2019 15:06:04 -0500
From:   Rob Herring <robh@...nel.org>
To:     Roger Quadros <rogerq@...com>
Cc:     kishon@...com, aniljoy@...ence.com, adouglas@...ence.com,
        nsekhar@...com, jsarha@...com, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 2/3] dt-bindings: phy: ti,phy-j721e-wiz: Add Type-C
 dir GPIO

On Thu, Oct 24, 2019 at 02:40:41PM +0300, Roger Quadros wrote:
> This is an optional GPIO, if specified will be used to
> swap lane 0 and lane 1 based on GPIO status. This is required
> to achieve plug flip support for USB Type-C.
> 
> Type-C companions typically need some time after the cable is
> plugged before and before they reflect the correct status of
> Type-C plug orientation on the DIR line.
> 
> Type-C Spec specifies CC attachment debounce time (tCCDebounce)
> of 100 ms (min) to 200 ms (max).
> 
> Allow the DT node to specify the time (in ms) that we need
> to wait before sampling the DIR line.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> Cc: Rob Herring <robh@...nel.org>
> ---
>  .../devicetree/bindings/phy/ti,phy-j721e-wiz.yaml | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/phy/ti,phy-j721e-wiz.yaml b/Documentation/devicetree/bindings/phy/ti,phy-j721e-wiz.yaml
> index 8a1eccee6c1d..5dab0010bcdf 100644
> --- a/Documentation/devicetree/bindings/phy/ti,phy-j721e-wiz.yaml
> +++ b/Documentation/devicetree/bindings/phy/ti,phy-j721e-wiz.yaml
> @@ -53,6 +53,21 @@ properties:
>    assigned-clock-parents:
>      maxItems: 2
>  
> +  typec-dir-gpios:

TI specific or could be generic?

> +    maxItems: 1
> +    description:
> +      GPIO to signal Type-C cable orientation for lane swap.
> +      If GPIO is active, lane 0 and lane 1 of SERDES will be swapped to
> +      achieve the funtionality of an exernal type-C plug flip mux.

s/exernal/external/

> +
> +  typec-dir-debounce:

Needs '-ms' suffix.

> +    $ref: '/schemas/types.yaml#/definitions/uint32'

then you can drop this because standard units have type already.

> +    description:
> +      Number of milliseconds to wait before sampling
> +      typec-dir-gpio. If not specified, the GPIO will be sampled ASAP.
> +      Type-C spec states minimum CC pin debounce of 100 ms and maximum
> +      of 200 ms.

Express this as constraints:

minimum: 100
maximum: 200
default: ???

If the spec minimum is 100ms, then doesn't sampling ASAP violate the 
spec?

> +
>  patternProperties:
>    "^pll[0|1]_refclk$":
>      type: object
> -- 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>