linux-kernel - Re: [PATCH v10 1/9] dt-bindings: opp: Introduce opp-level bindings

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Date:   Wed, 9 Jan 2019 14:50:42 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     andy.gross@...aro.org, robh@...nel.org, sboyd@...nel.org,
        ulf.hansson@...aro.org, collinsd@...eaurora.org, mka@...omium.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, henryc.chen@...iatek.com
Subject: Re: [PATCH v10 1/9] dt-bindings: opp: Introduce opp-level bindings



On 1/9/2019 2:39 PM, Viresh Kumar wrote:
> On 09-01-19, 14:34, Rajendra Nayak wrote:
>> On some SoCs (especially from Qualcomm and MediaTek) an OPP
>> node needs to describe an additional level/corner value
>> that is then communicated to a remote microprocessor by the CPU, which
>> then takes some actions (like adjusting voltage values across variousi
>> rails) based on the value passed.
>>
>> Add opp-level as an additional property in the OPP node and describe it
>> in the OPP bindings document.
>>
>> Signed-off-by: Rajendra Nayak <rnayak@...eaurora.org>
>> ---
>>   Documentation/devicetree/bindings/opp/opp.txt | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
>> index c396c4c0af92..e83fb7cbfd58 100644
>> --- a/Documentation/devicetree/bindings/opp/opp.txt
>> +++ b/Documentation/devicetree/bindings/opp/opp.txt
>> @@ -129,6 +129,11 @@ Optional properties:
>>   - opp-microamp-<name>: Named opp-microamp property. Similar to
>>     opp-microvolt-<name> property, but for microamp instead.
>>   
>> +- opp-level: On some SoC platforms an OPP node can describe a positive value
>> +  representing a corner/level that's communicated with a remote microprocessor
>> +  (usually called the power manager) which then translates it into a certain
>> +  voltage on a voltage rail.
>> +
> 
> This binding is generic enough and doesn't have anything to do with a
> remote mp and so such statements should be avoided in here. And then
> Linux can use it the way it wants.
> 
> Maybe just say that it describes the performance level of the device.
> That's all.

Sure, does this seem fine?

- opp-level: A value representing the performance level of the device,
   expressed as a 32-bit big-endian integer.

I assume the changelog mentioning the motivation behind adding this is fine?

> 
>>   - clock-latency-ns: Specifies the maximum possible transition latency (in
>>     nanoseconds) for switching to this OPP from any other OPP.
>>   
>> -- 
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation
> 

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation