Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20180627045234.27403-1-rnayak@codeaurora.org> <20180627045234.27403-3-rnayak@codeaurora.org>
 <20180703223554.GA32313@rob-hp-laptop> <20180704055757.4li26b6poxllmh2k@vireshk-i7>
 <1463d24b-481d-eecd-9e44-e7a5a993e5fc@codeaurora.org> <CAL_JsqJe+m4hD3nxQDjOT1JzRoSMXppy1r6APV1w=NtgCr-X_A@mail.gmail.com>
 <271db7b1-f65b-f42d-b00b-9362429b3749@codeaurora.org> <CAL_JsqJQypZbeZRa2u2+nM96p0ZHMHgDSpMbXqZx6zn+OiZSrw@mail.gmail.com>
 <20181004083637.xlz26rpn4qtsvdk7@vireshk-i7>
In-Reply-To: <20181004083637.xlz26rpn4qtsvdk7@vireshk-i7>
From:   Rob Herring <robh@kernel.org>
Date:   Thu, 4 Oct 2018 10:18:22 -0500
Message-ID: <CAL_JsqKSiT15sn_jXy0FRp_YG5XbkREUeHf-98A61iN-TKxWpQ@mail.gmail.com>
Subject: Re: [PATCH v4 2/6] dt-bindings: power: Add qcom rpm power domain
 driver bindings
To:     Viresh Kumar <viresh.kumar@linaro.org>
Cc:     Rajendra Nayak <rnayak@codeaurora.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Andy Gross <andy.gross@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        David Collins <collinsd@codeaurora.org>,
        Matthias Kaehlcke <mka@chromium.org>,
        devicetree@vger.kernel.org,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Oct 4, 2018 at 3:36 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 25-09-18, 14:43, Rob Herring wrote:
> > On Tue, Sep 25, 2018 at 5:25 AM Rajendra Nayak <rnayak@codeaurora.org> wrote:
> > >
> > > Hi Rob,
> > >
> > > []...
> > > >>>>> +   rpmhpd_opp_table: opp-table {
> > > >>>>> +           compatible = "operating-points-v2-qcom-level";
> > > >>>>> +
> > > >>>>> +           rpmhpd_opp_ret: opp1 {
> > > >>>>> +                   qcom,level = <RPMH_REGULATOR_LEVEL_RETENTION>;
> > > >>>>> +           };
> > > >>>>
> > > >>>> I don't see the point in using the OPP binding here when you aren't
> > > >>>> using *any* of the properties from it.
> > > >>>
> > > >>> Yeah, that's the case for now. But there are cases (as Stephen
> > > >>> mentioned earlier [1]) where the voltage values (and maybe other
> > > >>> values like current, etc) would be known and filled in DT. And that's
> > > >>> why we all agreed to use OPP tables for PM domains as well, as these
> > > >>> are really "operating performance points" of these PM domains.
> > > >>
> > > >> Rob, are you fine with these bindings then?
> > > >
> > > > Okay, my only thought is whether we should just use 'reg' here, or do
> > > > we need 'level' for anything else and should make it common?
> > >
> > > I am not quite sure I understood what you are suggesting here :(
> >
> > You could use the  'reg' property instead of 'qcom,level'. Any reason
> > not to do that?
>
> They can use any property which uniquely identifies the OPP nodes in
> the table. Though I never thought we can use 'reg' property in such a
> way. I always thought it must be related to registers somehow :)

That's almost certainly where the name originates from back in the
90s. I view 'reg' as how you identify or address a device. This can be
channels of something like an ADC.

It's perhaps a stretch for OPP nodes as they aren't really a device,
but if the levels are part of the h/w then perhaps reg is a good
match.

Rob