linux-kernel - Re: [PATCH 13/16] OPP: Extend dev_pm_opp

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Date:   Thu, 8 Jun 2023 16:15:40 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Cristian Marussi <cristian.marussi@....com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        Nikunj Kela <nkela@...cinc.com>,
        Prasad Sodagudi <psodagud@...cinc.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 13/16] OPP: Extend dev_pm_opp_data with OPP provider
 support

On 08-06-23, 11:37, Ulf Hansson wrote:
> The required opps are also different, as it's getting parsed from DT
> both for the genpd provider and the consumer. The point is, there are
> more code involved but just _set_required_opps().
> 
> For example, _set_performance_state() (which is the one that calls
> dev_pm_genpd_set_performance_state()) is designed to be used for
> required opps. Does it really make sense to rework
> _set_performance_state() so it can be used for this case too, just to
> avoid another call to dev_pm_genpd_set_performance_state() somewhere
> in the code?

What we need here, in you case, is really the required-opp thing, without the
DT parsing. The genpd will have an OPP table here, and devices (you are adding
OPP table dynamically for) shall have the genpd's OPPs as their required OPPs,
since for setting OPPs of the device, it is *required* to have OPP of the genpd
set too. Just like how it happens with DT. No special handling will be required
in dev_pm_opp_set_opp() path in this case and existing code will just work. You
just need to set the required-opp tables properly.

-- 
viresh