Re: [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI

From: Ulf Hansson <ulf.hansson@linaro.org>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	"Raju P . L . S . S . S . N" <rplsssn@codeaurora.org>,
	Amit Kucheria <amit.kucheria@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Niklas Cassel <niklas.cassel@linaro.org>,
	Tony Lindgren <tony@atomide.com>,
	Kevin Hilman <khilman@kernel.org>,
	Lina Iyer <ilina@codeaurora.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Souvik Chakravarty <souvik.chakravarty@arm.com>,
	Linux PM <linux-pm@vger.kernel.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI
Date: Tue, 18 Jun 2019 13:56:13 +0200	[thread overview]
Message-ID: <CAPDyKFpo8pJroOq=YkkNkt6+xyOdu3tTovEbsEp2ry0OJUu7JQ@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFqC8+Sv5WRhwOxqphAt8tb_PDisy13Miz5e-PajvwS1ew@mail.gmail.com>

On Mon, 10 Jun 2019 at 20:57, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> On Mon, 10 Jun 2019 at 19:16, Lorenzo Pieralisi
> <lorenzo.pieralisi@arm.com> wrote:
> >
> > On Mon, Jun 10, 2019 at 05:54:39PM +0200, Ulf Hansson wrote:
> >
> > [...]
> >
> > > My summary from the earlier ones, is that because the PSCI spec
> > > includes support for OSI, we should also support it in the kernel (and
> > > ATF). In a discussion offlist, Lorenzo agreed that it's okay to add,
> > > without an apple to apple comparison. Maybe Lorenzo can fill in and
> > > state this publicly, to save us all some time?
> >
> > The comparison should have been made before even requesting PSCI OSI
> > mode changes to the specifications, so we have a chip on our shoulders
> > anyway.
> >
> > We will enable PSCI OSI but that's not where the problem lies, enabling
> > PSCI OSI from a firmware perspective should take 10 lines of code,
> > not:
>
> Thanks for confirming!
>
> >
> >  drivers/firmware/psci/Makefile                |   2 +-
> >  drivers/firmware/psci/psci.c                  | 219 ++++++++--
> >  drivers/firmware/psci/psci.h                  |  29 ++
> >  drivers/firmware/psci/psci_pm_domain.c        | 403 ++++++++++++++++++
> >
> > I have some concerns about these changes that I will state in the
> > relevant patches.
>
> Most of the above changes isn't for solely for OSI, but to support a
> hierarchical topology described in the PSCI DT layout. This is for
> example needed when other resources shares the same power rail as the
> CPU cluster.
>
> In other words, the series is orthogonal to whether OSI or PC mode is
> used for PSCI, just to make that clear. BTW, this is what you
> requested me to change into, a while ago.
>
> >
> > > My final point in regards to the OSI mode support, it's a minor part
> > > of the series. I don't see how that should hurt from a maintenance
> > > point of view, or perhaps I am wrong? In any case, I offer my help
> > > with review/maintenance in any form as you may see need/fit.
> >
> > I will go through the series but most of this code should move
> > to core PM code, it has nothing to do with PSCI.
>
> I am looking forward to your review - and for sure, I am open to suggestions!
>
> >
> > BTW, apologies for the delay, I was away.

Lorenzo, a gentle ping.

Kind regards
Uffe