linux-kernel - Re: [PATCH] opp: Return genpd virtual devices from dev_pm_opp_attach

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Date:   Wed, 17 Jul 2019 15:44:04 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Rajendra Nayak <rnayak@...eaurora.org>
Cc:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] opp: Return genpd virtual devices from
 dev_pm_opp_attach_genpd()

On 17-07-19, 15:34, Rajendra Nayak wrote:
> 
> 
> On 7/17/2019 11:17 AM, Viresh Kumar wrote:
> > On 11-07-19, 15:09, Rajendra Nayak wrote:
> > > Sorry for the delay
> > 
> > Same here :)
> > 
> > > I seem to have completely missed this patch.
> > > I just gave this a try and here are some observations,
> > > 
> > > I have a case where I have one device with 2 power domains, one of them
> > > is scale-able (supports perf state) and the other one supports only being
> > > turned on and off.
> > > 
> > > 1. In the driver I now need to use dev_pm_domain_attach_by_name/id to attach the
> > > power domain which supports only on/off and then use dev_pm_opp_attach_genpd()
> > > for the one which supports perf states.
> > > 
> > > 2. My OPP table has only 1 required_opps, so the required_opp_count for the OPP table is 1.
> > > Now if my device tree has my scale-able powerdomain at index 1 (it works if its at index 0)
> > > then I end up with this error
> > > 
> > > [    2.858628] ufshcd-qcom 1d84000.ufshc: Index can't be greater than required-opp-count - 1, rpmh_pd (1 : 1)
> > > 
> > > so it looks like a lot of the OPP core today just assumes that if a device has multiple power domains,
> > > all of them are scale-able which isn't necessarily true.
> > 
> > I don't think a lot of OPP core has these problems, but maybe only
> > this place. I was taking care of this since the beginning just forgot
> > it now.
> > 
> > What about this over this commit:
> 
> Yes, this does seem to fix my concern mentioned in 2. above.

Great. I will include your Tested-by:, Lemme know if you have any
objections.

-- 
viresh