linux-kernel - Re: [PATCH v2 2/2] [RFC] CPUFreq: Add support for cpu-perf-dependencies

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Date:   Wed, 14 Oct 2020 09:55:31 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     Ionela Voinescu <ionela.voinescu@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Nicola Mazzucato <nicola.mazzucato@....com>,
        devicetree@...r.kernel.org, linux-pm@...r.kernel.org,
        vireshk@...nel.org, daniel.lezcano@...aro.org, rjw@...ysocki.net,
        linux-kernel@...r.kernel.org, robh+dt@...nel.org,
        chris.redpath@....com, morten.rasmussen@....com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] [RFC] CPUFreq: Add support for
 cpu-perf-dependencies

On 12-10-20, 18:18, Lukasz Luba wrote:
> On 10/12/20 5:52 PM, Ionela Voinescu wrote:
> > On Monday 12 Oct 2020 at 16:49:30 (+0100), Sudeep Holla wrote:
> > > On Fri, Oct 09, 2020 at 11:09:21AM +0530, Viresh Kumar wrote:
> > > > - I wonder if we can keep using that instead of creating new bindings
> > > >    for exact same stuff ? Though the difference here would be that the
> > > >    OPP may not have any other entries.
> > > 
> > > Well summarised, sorry for chiming in late. I could have not summarised
> > > any better. Just saw the big thread and was thinking of summarising.
> > > If the last point on OPP is possible(i.e. no OPP entries but just use
> > > it for fetch the information) for $subject patch is trying to achieve,
> > > then it would be good.

Under normal circumstances, I wouldn't have suggested empty opp-tables
for sure but it doesn't seem worth adding another binding to get this
information out :)

> > 
> > Just to put in my two pennies worth: using opp-shared (in possibly empty
> > OPP table) as alternative to cpu-perf-dependencies sounds good enough
> > to me as well.
> 
> +1

Now that (almost) everyone agrees, I don't think we need to make any
change anywhere, in code or bindings. This should work right now as
well.  The code should never try to create OPP tables and the core
will not create one. Your driver (which want to get this information
out of empty OPP tables) shall call dev_pm_opp_of_get_sharing_cpus(),
which just parses the DT to get this information out.

-- 
viresh