From: Sudeep Holla <sudeep.holla@arm.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
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>,
Bjorn Andersson <bjorn.andersson@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>,
Sudeep Holla <sudeep.holla@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 15/18] drivers: firmware: psci: Support CPU hotplug for the hierarchical model
Date: Mon, 10 Jun 2019 12:02:50 +0100 [thread overview]
Message-ID: <20190610110250.GD26602@e107155-lin> (raw)
In-Reply-To: <CAPDyKFqooMww0B6vGL56BnG-L=13C3oWeDFx4v1cO9=W9QPwVQ@mail.gmail.com>
On Mon, Jun 10, 2019 at 12:21:47PM +0200, Ulf Hansson wrote:
> On Fri, 7 Jun 2019 at 17:31, Sudeep Holla <sudeep.holla@arm.com> wrote:
> >
> > On Mon, May 13, 2019 at 09:22:57PM +0200, Ulf Hansson wrote:
> > > When the hierarchical CPU topology is used and when a CPU has been put
> > > offline (hotplug), that same CPU prevents its PM domain and thus also
> > > potential master PM domains, from being powered off. This is because genpd
> > > observes the CPU's attached device as being active from a runtime PM point
> > > of view.
> > >
> > > To deal with this, let's decrease the runtime PM usage count by calling
> > > pm_runtime_put_sync_suspend() of the attached struct device when putting
> > > the CPU offline. Consequentially, we must then increase the runtime PM
> > > usage count, while putting the CPU online again.
> > >
> >
> > Why is this firmware/driver specific ? Why can't this be dealt in core
> > pm-domain ? I am concerned that if any other architectures or firmware
> > method decides to use this feature, this need to be duplicated there.
>
> What is the core pm-domain? Do you refer to the generic PM domain (genpd), no?
>
Sorry for my bad choice of names. I just wrote names as I understand
rather than looking for exact match. But yes, I meant generic place
where such ref-counting is done currently for other things.
> In such case, this is not the job of genpd, but rather the opposite
> (to *monitor* the reference count).
>
OK, I need to understand that then.
> >
> > The way I see this is pure reference counting and is hardware/firmware/
> > driver agnostic and can be made generic.
>
> As stated in the another reply, I would rather start with having more
> things driver specific rather than generic. Later on we can always
> consider to move/split things, when there are more users.
>
> In this particular case, the runtime PM reference counting is done on
> the struct device*, that genpd returned via
> dev_pm_domain_attach_by_name(). And because
> dev_pm_domain_attach_by_name() is called from PSCI code, I decided to
> keep this struct device* internal to PSCI.
Sure, I understand your intent. I have just mentioned my thoughts/comments
as I reviewed.
--
Regards,
Sudeep
next prev parent reply other threads:[~2019-06-10 11:02 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-13 19:22 [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI Ulf Hansson
2019-05-13 19:22 ` [PATCH 01/18] dt: psci: Update DT bindings to support hierarchical PSCI states Ulf Hansson
2019-07-19 11:29 ` Lorenzo Pieralisi
2019-05-13 19:22 ` [PATCH 02/18] of: base: Add of_get_cpu_state_node() to get idle states for a CPU node Ulf Hansson
2019-05-13 19:22 ` [PATCH 03/18] cpuidle: dt: Support hierarchical CPU idle states Ulf Hansson
2019-05-13 19:22 ` [PATCH 04/18] ARM/ARM64: cpuidle: Let back-end init ops take the driver as input Ulf Hansson
2019-06-07 15:00 ` Sudeep Holla
2019-06-10 10:20 ` Ulf Hansson
2019-05-13 19:22 ` [PATCH 05/18] drivers: firmware: psci: Simplify state node parsing Ulf Hansson
2019-06-07 15:01 ` Sudeep Holla
2019-05-13 19:22 ` [PATCH 06/18] drivers: firmware: psci: Support hierarchical CPU idle states Ulf Hansson
2019-06-07 15:03 ` Sudeep Holla
2019-05-13 19:22 ` [PATCH 07/18] drivers: firmware: psci: Prepare to use OS initiated suspend mode Ulf Hansson
2019-06-07 15:17 ` Sudeep Holla
2019-06-10 10:21 ` Ulf Hansson
2019-06-10 10:42 ` Sudeep Holla
2019-07-16 14:53 ` Sudeep Holla
2019-05-13 19:22 ` [PATCH 08/18] drivers: firmware: psci: Prepare to support PM domains Ulf Hansson
2019-06-07 15:21 ` Sudeep Holla
2019-05-13 19:22 ` [PATCH 09/18] drivers: firmware: psci: Add support for PM domains using genpd Ulf Hansson
2019-06-07 15:27 ` Sudeep Holla
2019-06-10 10:21 ` Ulf Hansson
2019-06-10 10:59 ` Sudeep Holla
2019-07-16 15:05 ` Sudeep Holla
2019-07-18 11:04 ` Ulf Hansson
2019-07-18 13:19 ` Sudeep Holla
2019-07-18 17:57 ` Lina Iyer
2019-07-19 9:45 ` Sudeep Holla
2019-05-13 19:22 ` [PATCH 10/18] drivers: firmware: psci: Add hierarchical domain idle states converter Ulf Hansson
2019-07-09 15:31 ` Lorenzo Pieralisi
2019-07-16 8:45 ` Ulf Hansson
2019-07-16 14:51 ` Lorenzo Pieralisi
2019-07-18 11:43 ` Ulf Hansson
2019-07-18 13:36 ` Lorenzo Pieralisi
2019-05-13 19:22 ` [PATCH 11/18] drivers: firmware: psci: Introduce psci_dt_topology_init() Ulf Hansson
2019-05-13 19:22 ` [PATCH 12/18] drivers: firmware: psci: Add a helper to attach a CPU to its PM domain Ulf Hansson
2019-05-13 19:22 ` [PATCH 13/18] drivers: firmware: psci: Attach the CPU's device " Ulf Hansson
2019-05-13 19:22 ` [PATCH 14/18] drivers: firmware: psci: Manage runtime PM in the idle path for CPUs Ulf Hansson
2019-07-16 15:53 ` Lorenzo Pieralisi
2019-07-18 10:35 ` Ulf Hansson
2019-07-18 13:30 ` Lorenzo Pieralisi
2019-07-18 16:54 ` Ulf Hansson
2019-07-18 17:41 ` Lina Iyer
2019-07-18 21:49 ` Ulf Hansson
2019-07-19 10:02 ` Lorenzo Pieralisi
2019-05-13 19:22 ` [PATCH 15/18] drivers: firmware: psci: Support CPU hotplug for the hierarchical model Ulf Hansson
2019-06-07 15:31 ` Sudeep Holla
2019-06-10 10:21 ` Ulf Hansson
2019-06-10 11:02 ` Sudeep Holla [this message]
2019-05-13 19:22 ` [PATCH 16/18] arm64: kernel: Respect the hierarchical CPU topology in DT for PSCI Ulf Hansson
2019-05-13 19:22 ` [PATCH 17/18] arm64: dts: Convert to the hierarchical CPU topology layout for MSM8916 Ulf Hansson
2019-07-16 14:47 ` Sudeep Holla
2019-07-16 20:36 ` Lina Iyer
2019-07-17 17:18 ` Sudeep Holla
2019-05-13 19:23 ` [PATCH 18/18] arm64: dts: hikey: Convert to the hierarchical CPU topology layout Ulf Hansson
2019-07-16 14:47 ` Sudeep Holla
2019-07-18 10:48 ` Ulf Hansson
2019-07-18 13:11 ` Sudeep Holla
2019-05-14 8:08 ` [PATCH 00/18] ARM/ARM64: Support hierarchical CPU arrangement for PSCI Rafael J. Wysocki
2019-05-14 8:58 ` Ulf Hansson
2019-06-07 15:42 ` Sudeep Holla
2019-06-07 19:34 ` Bjorn Andersson
2019-06-10 10:32 ` Sudeep Holla
2019-06-10 15:54 ` Ulf Hansson
2019-06-10 17:16 ` Lorenzo Pieralisi
2019-06-10 18:57 ` Ulf Hansson
2019-06-18 11:56 ` Ulf Hansson
2019-06-07 11:19 ` Ulf Hansson
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