linux-kernel - Re: [RFC/PATCH 0/5] DVFS in the OPP core

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Message-ID: <20190208071726.urevxs5a3vaf7gwh@vireshk-i7>
Date:   Fri, 8 Feb 2019 12:47:26 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Stephen Boyd <swboyd@...omium.org>,
        Graham Roff <grahamr@...eaurora.org>,
        Mike Turquette <mturquette@...libre.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        linux-serial@...r.kernel.org, linux-spi@...r.kernel.org,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Doug Anderson <dianders@...omium.org>,
        Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [RFC/PATCH 0/5] DVFS in the OPP core

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.

> Even it this may be fairly uncommon, we should consider it, before we
> decide to fold in additional clock management, like
> clk_prepare|unprepare() for example, behind the dev_pm_opp_set_rate()
> API.
> 
> The point is, the driver may need to call clk_prepare|enable()
> anyways, unless we make that conditional depending on a DT compatible
> string, for example. Of course, because the clock prepare/enable is
> reference counted, there may not be a problem in practice to have both
> the OPP and driver to deal with it.

-- 
viresh