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From:   Saravana Kannan <saravanak@google.com>
Date:   Tue, 16 Jul 2019 11:58:08 -0700
Message-ID: <CAGETcx9KSqvyzbM-S8LvBObkNBt38K683Ljm8nNQuhxk7MuvAg@mail.gmail.com>
Subject: Re: [PATCH v3 1/6] dt-bindings: opp: Introduce opp-peak-KBps and
 opp-avg-KBps bindings
To:     Sibi Sankar <sibis@codeaurora.org>
Cc:     Georgi Djakov <georgi.djakov@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Stephen Boyd <sboyd@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        "Sweeney, Sean" <seansw@qti.qualcomm.com>,
        daidavid1@codeaurora.org, Rajendra Nayak <rnayak@codeaurora.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Evan Green <evgreen@chromium.org>,
        Android Kernel Team <kernel-team@android.com>,
        Linux PM <linux-pm@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
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On Tue, Jul 16, 2019 at 10:25 AM Sibi Sankar <sibis@codeaurora.org> wrote:
>
> Hey Saravana,
>
> https://patchwork.kernel.org/patch/10850815/
> There was already a discussion ^^ on how bandwidth bindings were to be
> named.

Yes, I'm aware of that series. That series is trying to define a BW
mapping for an existing frequency OPP table. This patch is NOT about
adding a mapping to an existing table. This patch is about adding the
notion of BW OPP tables where BW is the "key" instead of "frequency".

So let's not mixed up these two series.

-Saravana

> On 7/3/19 6:40 AM, 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 replace 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@google.com>
> > ---
> >   Documentation/devicetree/bindings/opp/opp.txt | 15 ++++++++++++---
> >   1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> > index 76b6c79604a5..c869e87caa2a 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 but for devices like power domains or
> > +  bandwidth opp tables. 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-bw 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. For example, bandwidth OPP tables for interconnect paths.
> >
> >   Optional properties:
> >   - opp-microvolt: voltage in micro Volts.
> > @@ -132,6 +137,10 @@ Optional properties:
> >   - opp-level: A value representing the performance level of the device,
> >     expressed as a 32-bit integer.
> >
> > +- opp-avg-KBps: Average bandwidth in kilobytes per second, expressed as a
> > +  32-bit big-endian integer. This property is only meaningful in OPP tables
> > +  where opp-peak-KBps is present.
> > +
> >   - clock-latency-ns: Specifies the maximum possible transition latency (in
> >     nanoseconds) for switching to this OPP from any other OPP.
> >
> >
>
> --
> Qualcomm Innovation Center, Inc.
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