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

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Date:   Mon, 28 Oct 2019 10:32:16 +0200
From:   Roger Quadros <rogerq@...com>
To:     Rob Herring <robh@...nel.org>
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

Hi Rob,

On 25/10/2019 23:06, Rob Herring wrote:
> 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?

This driver is TI only.

> 
>> +    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?

Good point. I'll change the default to 100.

Some board solutions seem to take even longer than 200. I can set
1000 ms as maximum.

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

--
cheers,
-roger
  
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki