linux-kernel - Re: [PATCH 2/2] OPP/pmdomain: Fix the assignment of the required-devs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKohponJsqOYAvQqU2qrBCXv_P0+0zKAm7-5gkKGPsF_kT7L0w@mail.gmail.com>
Date: Wed, 11 Sep 2024 11:32:49 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>, 
	Dikshita Agarwal <quic_dikshita@...cinc.com>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <quic_kdybcio@...cinc.com>, Nikunj Kela <nkela@...cinc.com>, 
	"Bryan O'Donoghue" <bryan.odonoghue@...aro.org>, Thierry Reding <thierry.reding@...il.com>, 
	Mikko Perttunen <mperttunen@...dia.com>, Jonathan Hunter <jonathanh@...dia.com>, 
	Stephan Gerhold <stephan@...hold.net>, Ilia Lin <ilia.lin@...nel.org>, 
	Stanimir Varbanov <stanimir.k.varbanov@...il.com>, Vikash Garodia <quic_vgarodia@...cinc.com>, 
	linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] OPP/pmdomain: Fix the assignment of the required-devs

FYI, I am on holidays now :)

On Fri, 6 Sept 2024 at 14:19, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> > How do we differentiate between two cases where the required-opps can
> > be defined as either of these:
> >
> > required-opps = <&opp_pd_50, &opp_pd_51>; //corresponds to pd_perf1 and pd_perf0 (in reverse order)
> >
> > OR
> >
> > required-opps = <&opp_pd_51, &opp_pd_50>; //corresponds to pd_perf0 and pd_perf1
> >
> > I thought this can't be fixed without some platform code telling how
> > the DT is really configured, i.e. order of the power domains in the
> > required-opps.
>
> I don't think we need platform code for this.
>
> When registering a genpd provider, an OPP table gets assigned to it.

So we will create a real OPP table in code, which will point to the common
OPP table in DT. Fine.

> When hooking up a device to one of its genpd providers, that virtual
> device then also gets a handle to its genpd's OPP table.

Right.

If there are two genpds required for a device from the same genpd provider, the
picture isn't very clear at this point. i.e. which required OPP
belongs to which genpd,
as both have same table in DT.

> Each of the phandles in the required-opps points to another OPP table,
> which OPP table should be associated with a specific genpd.

Yes, but a simple order reversal in DT (which I sent in my last
email), will not be picked
by code at all. i.e. DT doesn't give the order in which required OPPs
are present.

> In other words, the information is there, we should not need anything
> additional in DT.