linux-kernel - Re: [RFC 1/2] dt-bindings: connector: Add property to set pd timer values

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Message-ID: <c858c534-98d6-4603-819e-9134dbed94cf@linaro.org>
Date: Mon, 16 Sep 2024 18:05:43 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Amit Sunil Dhamne <amitsd@...gle.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
 conor+dt@...nel.org, heikki.krogerus@...ux.intel.com,
 gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
 kyletso@...gle.com, rdbabiera@...gle.com,
 Badhri Jagan Sridharan <badhri@...gle.com>, linux-usb@...r.kernel.org,
 devicetree@...r.kernel.org
Subject: Re: [RFC 1/2] dt-bindings: connector: Add property to set pd timer
 values

On 13/09/2024 01:26, Amit Sunil Dhamne wrote:
> Hi Dmitry,
> 
> On 9/12/24 3:05 AM, Dmitry Baryshkov wrote:
>> On Tue, Sep 10, 2024 at 05:07:05PM GMT, Amit Sunil Dhamne wrote:
>>> This commit adds a new property "pd-timers" to enable setting of
>>> platform/board specific pd timer values for timers that have a range of
>>> acceptable values.
>>>
>>> Cc: Badhri Jagan Sridharan <badhri@...gle.com>
>>> Cc: linux-usb@...r.kernel.org
>>> Cc: devicetree@...r.kernel.org
>>> Signed-off-by: Amit Sunil Dhamne <amitsd@...gle.com>
>>> ---
>>>   .../bindings/connector/usb-connector.yaml     | 23 +++++++++++++++++++
>>>   include/dt-bindings/usb/pd.h                  |  8 +++++++
>>>   2 files changed, 31 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>>> index fb216ce68bb3..9be4ed12f13c 100644
>>> --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
>>> +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
>>> @@ -253,6 +253,16 @@ properties:
>>>   
>>>       additionalProperties: false
>>>   
>>> +  pd-timers:
>>> +    description: An array of u32 integers, where an even index (i) is the timer (referenced in
>>> +      dt-bindings/usb/pd.h) and the odd index (i+1) is the timer value in ms (refer
>>> +      "Table 6-68 Time Values" of "USB Power Delivery Specification Revision 3.0, Version 1.2 " for
>>> +      the appropriate value). For certain timers the PD spec defines a range rather than a fixed
>>> +      value. The timers may need to be tuned based on the platform. This dt property allows the user
>>> +      to assign specific values based on the platform. If these values are not explicitly defined,
>>> +      TCPM will use a valid default value for such timers.
>>> +    $ref: /schemas/types.yaml#/definitions/uint32-array
>> Is it really necessary to use the array property? I think it's easier
>> and more logical to define corresponding individual properties, one per
>> the timer.
> 
> Thanks for the review. The reason I did it this way was for
> convenience. If in the future someone else wants add a new timer,
> it'd be convenient to just add it as a new macro definition in pd.h
> rather than having to define a new property each time, especially
> if folks want to add more timers (scales better).
> There are 3 timers already and I am working to add a fourth in a
> follow up patch if the current RFC gets accepted.
> 
> Please let me know what do you think?

Binding is supposed to be complete. You already know this is not complete...

Best regards,
Krzysztof