linux-kernel - Re: [PATCH v6 1/3] dt-bindings: opp: Introduce opp-peak-kBps and opp-avg-kBps bindings

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Message-ID: <CAGETcx-fcKmMj4YF7U+zqr47zhAVoSTG_2R-1szik6nVqLykhg@mail.gmail.com>
Date:   Wed, 8 Jan 2020 16:32:03 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "Sweeney, Sean" <seansw@....qualcomm.com>,
        David Dai <daidavid1@...eaurora.org>, adharmap@...eaurora.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Evan Green <evgreen@...omium.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v6 1/3] dt-bindings: opp: Introduce opp-peak-kBps and
 opp-avg-kBps bindings

On Wed, Jan 8, 2020 at 2:32 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 06-12-19, 16:24, Saravana Kannan wrote:
> > Interconnects often quantify their performance points in terms of
> > bandwidth. So, add opp-peak-kBps (required) and opp-avg-kBps (optional) to
> > allow specifying Bandwidth OPP tables in DT.
> >
> > opp-peak-kBps is a required property that replaces opp-hz for Bandwidth OPP
> > tables.
> >
> > opp-avg-kBps is an optional property that can be used in Bandwidth OPP
> > tables.
> >
> > Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> > Reviewed-by: Rob Herring <robh@...nel.org>
> > ---
> >  Documentation/devicetree/bindings/opp/opp.txt     | 15 ++++++++++++---
> >  .../devicetree/bindings/property-units.txt        |  4 ++++
> >  2 files changed, 16 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> > index 68592271461f..dbad8eb6c746 100644
> > --- a/Documentation/devicetree/bindings/opp/opp.txt
> > +++ b/Documentation/devicetree/bindings/opp/opp.txt
> > @@ -83,9 +83,14 @@ properties.
> >
> >  Required properties:
> >  - opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer. This is a
> > -  required property for all device nodes but devices like power domains. The
> > -  power domain nodes must have another (implementation dependent) property which
> > -  uniquely identifies the OPP nodes.
> > +  required property for all device nodes except for devices like power domains
> > +  or bandwidth opp tables.
>
> Fine until here.
>
> > The power domain nodes must have another
> > +  (implementation dependent) property which uniquely identifies the OPP nodes.
> > +  The interconnect opps are required to have the opp-peak-kBps property.
>
> Maybe rewrite it as:
>
> The devices which don't have this property must have another
> (implementation dependent) property which uniquely identifies the OPP
> nodes.
>
> So we won't be required to update this again for another property.
>
> > +
> > +- opp-peak-kBps: Peak bandwidth in kilobytes per second, expressed as a 32-bit
> > +  big-endian integer.
>
> > This is a required property for all devices that don't
> > +  have opp-hz.
>
> This statement is surely incorrect, isn't it ? What about power-domain
> tables ?
>
> Suggest rewriting it as:
>
> This is a required property for bandwidth OPP tables.
>

Agree with all the suggestions. Will fix in the next version.

-Saravana