From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ulf Hansson <ulf.hansson@linaro.org>
Subject: Re: [RFC/PATCH 0/5] DVFS in the OPP core
Date: Fri, 8 Feb 2019 11:31:13 +0100
Message-ID: <CAPDyKFpmZNW7KgsgagD_6tKTQ07AJS7Kc=AGCQmMpNASuOG-Dg@mail.gmail.com>
References: <20190129015547.213276-1-swboyd@chromium.org> <20190131092349.fksfqemm23qddkhw@vireshk-i7>
 <154952629766.115909.11259861549408107064@swboyd.mtv.corp.google.com>
 <CAPDyKFrrncpfEfbZJ1LHvqDbkc29CaJxZnXwh4Mz7PT6Efbctg@mail.gmail.com>
 <20190208071726.urevxs5a3vaf7gwh@vireshk-i7> <CAPDyKFrXWAzDChd3d2acQnF6GZw57+g6XeNtHo29q3i1qjidnQ@mail.gmail.com>
 <20190208100529.l2y75ua3bfa6nnyx@vireshk-i7>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Cc: Stephen Boyd <swboyd@chromium.org>,
        Graham Roff <grahamr@codeaurora.org>,
        Mike Turquette <mturquette@baylibre.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        linux-serial@vger.kernel.org, linux-spi@vger.kernel.org,
        Rajendra Nayak <rnayak@codeaurora.org>,
        Doug Anderson <dianders@chromium.org>,
        Vincent Guittot <vincent.guittot@linaro.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20190208100529.l2y75ua3bfa6nnyx@vireshk-i7>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: linux-spi.vger.kernel.org

On Fri, 8 Feb 2019 at 11:05, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 08-02-19, 10:45, Ulf Hansson wrote:
> > On Fri, 8 Feb 2019 at 08:17, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > >
> > > On 07-02-19, 14:37, Ulf Hansson wrote:
> > > > I think we also need to consider cross SoC drivers. One SoC may have
> > > > both clocks and OPPs to manage, while another may have only clocks.
> > >
> > > We already have that case with CPUs as well and dev_pm_opp_set_rate()
> > > takes care of it.
> >
> > I think you may have misunderstood my point. Or maybe I don't get yours. :-)
>
> It was me. I thought you are talking about regulators and that is what
> is already managed, i.e. to work with or without regulators.
>
> > What if there is no OPP at all to use, then dev_pm_opp_set_rate() is
> > just a noop, right? In this scenario the driver still need to call
> > clk_set_rate().
> >
> > How do we cope with these cases?
>
> Yeah, that would be a problem and hacking the OPP core may not be the
> right solution :(

I guess one simple way forward could just be to check if there is an
OPP handle/table available, then use dev_pm_opp_set_rate(). When no
OPP handle/table, use clk_set_rate() *instead*, not both.

That could work, don't you think?

Kind regards
Uffe