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From: Ulf Hansson <ulf.hansson@linaro.org>
To: Sudeep Holla <sudeep.holla@arm.com>
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>,
	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>,
	Lina Iyer <lina.iyer@linaro.org>
Subject: Re: [PATCH 09/18] drivers: firmware: psci: Add support for PM domains using genpd
Date: Thu, 18 Jul 2019 13:04:03 +0200
Message-ID: <CAPDyKFqaE2L419siFY=LGDsotAnpBt+H_vpmG62AqQw8UQJZJA@mail.gmail.com> (raw)
In-Reply-To: <20190716150533.GD7250@e107155-lin>

On Tue, 16 Jul 2019 at 17:05, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Mon, May 13, 2019 at 09:22:51PM +0200, Ulf Hansson wrote:
> > When the hierarchical CPU topology layout is used in DT, we need to setup
> > the corresponding PM domain data structures, as to allow a CPU and a group
> > of CPUs to be power managed accordingly. Let's enable this by deploying
> > support through the genpd interface.
> >
> > Additionally, when the OS initiated mode is supported by the PSCI FW, let's
> > also parse the domain idle states DT bindings as to make genpd responsible
> > for the state selection, when the states are compatible with
> > "domain-idle-state". Otherwise, when only Platform Coordinated mode is
> > supported, we rely solely on the state selection to be managed through the
> > regular cpuidle framework.
> >
> > If the initialization of the PM domain data structures succeeds and the OS
> > initiated mode is supported, we try to switch to it. In case it fails,
> > let's fall back into a degraded mode, rather than bailing out and returning
> > an error code.
> >
> > Due to that the OS initiated mode may become enabled, we need to adjust to
> > maintain backwards compatibility for a kernel started through a kexec call.
> > Do this by explicitly switch to Platform Coordinated mode during boot.
> >
> > Finally, the actual initialization of the PM domain data structures, is
> > done via calling the new shared function, psci_dt_init_pm_domains().
> > However, this is implemented by subsequent changes.
> >
> > Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
> > Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> > ---
> >
> > Changes:
> >       - Simplify code setting domain_state at power off.
> >       - Use the genpd ->free_state() callback to manage freeing of states.
> >       - Fixup a bogus while loop.
> >
> > ---
> >  drivers/firmware/psci/Makefile         |   2 +-
> >  drivers/firmware/psci/psci.c           |   7 +-
> >  drivers/firmware/psci/psci.h           |   5 +
> >  drivers/firmware/psci/psci_pm_domain.c | 268 +++++++++++++++++++++++++
> >  4 files changed, 280 insertions(+), 2 deletions(-)
> >  create mode 100644 drivers/firmware/psci/psci_pm_domain.c
> >
>
> [...]
>
> >  #endif /* __PSCI_H */
> > diff --git a/drivers/firmware/psci/psci_pm_domain.c b/drivers/firmware/psci/psci_pm_domain.c
> > new file mode 100644
> > index 000000000000..3c6ca846caf4
> > --- /dev/null
> > +++ b/drivers/firmware/psci/psci_pm_domain.c
> > @@ -0,0 +1,268 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * PM domains for CPUs via genpd - managed by PSCI.
> > + *
> > + * Copyright (C) 2019 Linaro Ltd.
> > + * Author: Ulf Hansson <ulf.hansson@linaro.org>
> > + *
> > + */
> > +
>
> [...]
>
> > +static int psci_pd_power_off(struct generic_pm_domain *pd)
> > +{
> > +     struct genpd_power_state *state = &pd->states[pd->state_idx];
> > +     u32 *pd_state;
> > +
> > +     /* If we have failed to enable OSI mode, then abort power off. */
> > +     if (psci_has_osi_support() && !osi_mode_enabled)
> > +             return -EBUSY;
> > +
> > +     if (!state->data)
> > +             return 0;
> > +
> > +     /* When OSI mode is enabled, set the corresponding domain state. */
> > +     pd_state = state->data;
> > +     psci_set_domain_state(*pd_state);
>
> I trying to understand how would this scale to level 2(cluster of
> clusters or for simply system). The current code for psci_set_domain_state
> just stores the value @pd_state into per-cpu domain_state. E.g.: Now if
> the system level pd is getting called after cluster PD, it will set the
> domain state to system level PD state. It won't work with original
> format and it may work with extended format if it's carefully crafted.
> In short, the point is just over-writing domain_state is asking for
> troubles IMO.

Thanks for spotting this!

While walking upwards in the PM domain topology, I thought I was ORing
the domain states, but clearly the code isn't doing that.

In principle we need to do the below instead.

pd_state = state->data;
composite_pd_state = *pd_state | psci_get_domain_state();
psci_set_domain_state(composite_pd_state);

Kind regards
Uffe

  reply index

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 [this message]
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
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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