linux-kernel - Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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Message-ID: <e452c0b5-5555-d6e2-40da-6aa21a26766d@codeaurora.org>
Date:   Wed, 11 Aug 2021 15:30:46 +0530
From:   Rajendra Nayak <rnayak@...eaurora.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Roja Rani Yarubandi <rojay@...eaurora.org>,
        Stephan Gerhold <stephan@...hold.net>
Subject: Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to
 set default perf state


On 8/10/2021 8:13 AM, Viresh Kumar wrote:
> On 09-08-21, 16:38, Rajendra Nayak wrote:
>> Sure, I can do that, apart from the error print, the function currently also
>> returns a -EINVAL in case of the missing 'required-opps', are we suggesting
>> we change that to not return an error also?
> 
> No.
> 
>> Since this is completely optional in the device node, we would want the function to
>> ideally not return error and only do so in case 'required-opps' exists and the
>> translation to performance state fails.
> 
> Not really. The function should return failure if the property isn't
> there, but it shouldn't be EINVAL but ENODEV.

In my case I don't want to error out if the property is missing, I want to error out
only when the property exists but can't be translated into a performance state.

So currently I check if the property exists and *only then* try to translate it, Ulf asked
me to skip the check. If I do that and I call of_get_required_opp_performance_state()
unconditionally, and if it errors out I will need to put in additional logic (check for
return value of ENODEV) to distinguish between the property-does-not-exist vs
property-exists-but-cannot-be-translated case.
It just seems more straight-forward to call this only when the property exists, Ulf?
  

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