From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Linux PM list <linux-pm@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Aaron Lu <aaron.lu@intel.com>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH 1/3] PM / sleep: Flag to speed up suspend-resume of runtime-suspended devices
Date: Thu, 08 May 2014 13:44:54 +0200 [thread overview]
Message-ID: <2321901.5eTtTCbUUZ@vostro.rjw.lan> (raw)
In-Reply-To: <CAPDyKFoPxXVYfK2ytGVJ8fYQDJXiSuaRX_6QtRYzffZVtKJfeA@mail.gmail.com>
On Thursday, May 08, 2014 12:59:20 PM Ulf Hansson wrote:
> On 8 May 2014 12:53, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > On Thursday, May 08, 2014 09:49:36 AM Ulf Hansson wrote:
> >> On 8 May 2014 01:29, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> >> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >> >
> >> > Currently, some subsystems (e.g. PCI and the ACPI PM domain) have to
> >> > resume all runtime-suspended devices during system suspend, mostly
> >> > because those devices may need to be reprogrammed due to different
> >> > wakeup settings for system sleep and for runtime PM.
> >> >
> >> > For some devices, though, it's OK to remain in runtime suspend
> >> > throughout a complete system suspend/resume cycle (if the device was in
> >> > runtime suspend at the start of the cycle). We would like to do this
> >> > whenever possible, to avoid the overhead of extra power-up and power-down
> >> > events.
> >> >
> >> > However, problems may arise because the device's descendants may require
> >> > it to be at full power at various points during the cycle. Therefore the
> >> > most straightforward way to do this safely is if the device and all its
> >> > descendants can remain runtime suspended until the resume stage of system
> >> > resume.
> >> >
> >> > To this end, introduce dev->power.leave_runtime_suspended.
> >> > If a subsystem or driver sets this flag during the ->prepare() callback,
> >> > and if the flag is set in all of the device's descendants, and if the
> >> > device is still in runtime suspend at the beginning of the ->suspend()
> >> > callback, that callback is allowed to return 0 without clearing
> >> > power.leave_runtime_suspended and without changing the state of the
> >> > device, unless the current state of the device is not appropriate for
> >> > the upcoming system sleep state (for example, the device is supposed to
> >> > wake up the system from that state and its current wakeup settings are
> >> > not suitable for that). Then, the PM core will not invoke the device's
> >> > ->suspend_late(), ->suspend_irq(), ->resume_irq(), ->resume_early(), or
> >> > ->resume() callbacks. Instead, it will invoke ->runtime_resume() during
> >> > the device resume stage of system resume.
> >> >
> >> > By leaving this flag set after ->suspend(), a driver or subsystem tells
> >> > the PM core that the device is runtime suspended, it is in a suitable
> >> > state for system suspend (for example, the wakeup setting does not
> >> > need to be changed), and it does not need to return to full
> >> > power until the resume stage.
> >> >
> >> > Changelog based on an Alan Stern's description of the idea
> >> > (http://marc.info/?l=linux-pm&m=139940466625569&w=2).
> >> >
> >> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >> > ---
> >> > drivers/base/power/main.c | 31 ++++++++++++++++++++++++-------
> >> > drivers/base/power/runtime.c | 10 ++++++++++
> >> > include/linux/pm.h | 3 +++
> >> > include/linux/pm_runtime.h | 16 ++++++++++++++++
> >> > kernel/power/Kconfig | 4 ++++
> >> > 5 files changed, 57 insertions(+), 7 deletions(-)
> >> >
> >> > Index: linux-pm/kernel/power/Kconfig
> >> > ===================================================================
> >> > --- linux-pm.orig/kernel/power/Kconfig
> >> > +++ linux-pm/kernel/power/Kconfig
> >> > @@ -147,6 +147,10 @@ config PM
> >> > def_bool y
> >> > depends on PM_SLEEP || PM_RUNTIME
> >> >
> >> > +config PM_BOTH
> >> > + def_bool y
> >> > + depends on PM_SLEEP && PM_RUNTIME
> >> > +
> >>
> >> Should we not depend on PM_RUNTIME only? Thus we don't need the new
> >> Kconfig,
> >
> > Well, OK. I guess we can tolerate one useless statement in rpm_resume()
> > in case CONFIG_PM_SLEEP is unset.
> >
> >> and then we could rename the new APIs to pm_runtime_* instead.
> >
> > That would just make the name longer - for what value?
>
> Only "__set_leave_runtime_suspended" will be a bit longer.
>
> The idea I had was to clearly indicate, these functions is a part of
> PM_RUNTIME API.
>
> Compare what you have:
> __set_leave_runtime_suspended
> pm_set_leave_runtime_suspended
> pm_leave_runtime_suspended
>
> To what I suggest:
> __pm_runtime_set_leave_suspended
> pm_runtime_set_leave_suspended
> pm_runtime_leave_suspended
And why exactly do you think these are any better?
The flag is not called leave_suspended surely?
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
next prev parent reply other threads:[~2014-05-08 11:28 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-14 23:12 [RFC][PATCH 0/3] PM: Mechanism to avoid resuming runtime-suspended devices during system suspend Rafael J. Wysocki
2014-01-14 23:13 ` [RFC][PATCH 1/3] PM / sleep: Flag to avoid executing suspend callbacks for devices Rafael J. Wysocki
2014-01-14 23:14 ` [RFC][PATCH 2/3] PM / runtime: Routine for checking device status during system suspend Rafael J. Wysocki
2014-01-16 13:32 ` Mika Westerberg
2014-01-16 16:07 ` [Update][RFC][PATCH " Rafael J. Wysocki
2014-01-14 23:16 ` [RFC][PATCH 3/3] ACPI / PM: Avoid resuming devices in ACPI PM domain " Rafael J. Wysocki
2014-01-15 13:57 ` [Update][RFC][PATCH " Rafael J. Wysocki
2014-02-16 23:49 ` [RFC][PATCH 0/3] PM: Mechanism to avoid resuming runtime-suspended devices " Rafael J. Wysocki
2014-02-16 23:50 ` [PATCH 1/3] PM / sleep: New flag to speed up suspend-resume of suspended devices Rafael J. Wysocki
2014-02-18 12:59 ` Ulf Hansson
2014-02-18 13:25 ` Rafael J. Wysocki
2014-02-19 17:01 ` Alan Stern
2014-02-20 1:23 ` Rafael J. Wysocki
2014-02-20 1:42 ` Rafael J. Wysocki
2014-02-20 17:03 ` Alan Stern
2014-02-24 0:00 ` Rafael J. Wysocki
2014-02-24 19:36 ` Alan Stern
2014-02-25 0:07 ` Rafael J. Wysocki
2014-02-25 17:08 ` Alan Stern
2014-02-25 23:56 ` Rafael J. Wysocki
2014-02-26 16:49 ` Alan Stern
2014-02-26 21:44 ` Rafael J. Wysocki
2014-02-26 22:17 ` Alan Stern
2014-02-26 23:13 ` Rafael J. Wysocki
2014-02-27 15:02 ` Alan Stern
2014-04-24 22:36 ` [RFC][PATCH 0/3] PM: Mechanism to avoid resuming runtime-suspended devices during system suspend, v2 Rafael J. Wysocki
2014-04-24 22:37 ` [RFC][PATCH 1/3] PM / sleep: Flags to speed up suspend-resume of runtime-suspended devices Rafael J. Wysocki
2014-05-01 21:39 ` Alan Stern
2014-05-01 23:15 ` Rafael J. Wysocki
2014-05-01 23:36 ` Rafael J. Wysocki
2014-05-02 0:04 ` Rafael J. Wysocki
2014-05-02 15:41 ` Rafael J. Wysocki
2014-05-02 18:44 ` Alan Stern
2014-05-05 0:09 ` Rafael J. Wysocki
2014-05-05 15:46 ` Alan Stern
2014-05-06 1:31 ` Rafael J. Wysocki
2014-05-06 19:31 ` Alan Stern
2014-05-07 0:36 ` Rafael J. Wysocki
2014-05-07 15:43 ` Alan Stern
2014-05-07 23:27 ` [RFC][PATCH 0/3] (was: Re: [RFC][PATCH 1/3] PM / sleep: Flags to speed up suspend-resume of runtime-suspended devices) Rafael J. Wysocki
2014-05-07 23:29 ` [RFC][PATCH 1/3] PM / sleep: Flag to speed up suspend-resume of runtime-suspended devices Rafael J. Wysocki
2014-05-08 7:49 ` Ulf Hansson
2014-05-08 10:53 ` Rafael J. Wysocki
2014-05-08 10:59 ` Ulf Hansson
2014-05-08 11:44 ` Rafael J. Wysocki [this message]
2014-05-08 12:25 ` Ulf Hansson
2014-05-08 20:02 ` Rafael J. Wysocki
2014-05-08 14:36 ` Alan Stern
2014-05-08 14:57 ` Alan Stern
2014-05-08 20:17 ` Rafael J. Wysocki
2014-05-08 21:03 ` Rafael J. Wysocki
2014-05-08 21:20 ` Alan Stern
2014-05-08 21:42 ` Rafael J. Wysocki
2014-05-08 21:50 ` Rafael J. Wysocki
2014-05-08 22:28 ` [RFC][PATCH 0/3] (was: Re: PM / sleep: Flag to speed up suspend-resume of runtime-suspended devices) Rafael J. Wysocki
2014-05-08 22:41 ` [RFC][PATCH 1/3] PM / sleep: Flag to speed up suspend-resume of runtime-suspended devices Rafael J. Wysocki
2014-05-09 7:23 ` Ulf Hansson
2014-05-09 11:33 ` Rafael J. Wysocki
2014-05-08 22:41 ` [RFC][PATCH 2/3] PM / runtime: Routine for checking device status during system suspend Rafael J. Wysocki
2014-05-08 22:42 ` [RFC][PATCH 3/3] ACPI / PM: Avoid resuming devices in ACPI PM domain " Rafael J. Wysocki
2014-05-09 1:52 ` [RFC][PATCH 1/3] PM / sleep: Flag to speed up suspend-resume of runtime-suspended devices Alan Stern
2014-05-09 22:49 ` Rafael J. Wysocki
2014-05-11 16:46 ` Alan Stern
2014-05-13 0:51 ` Rafael J. Wysocki
2014-05-08 21:08 ` Alan Stern
2014-05-09 22:48 ` Kevin Hilman
2014-05-10 1:38 ` Rafael J. Wysocki
2014-05-12 16:33 ` Kevin Hilman
2014-05-07 23:31 ` [Resend][PATCH 2/3] PM / runtime: Routine for checking device status during system suspend Rafael J. Wysocki
2014-05-07 23:33 ` [RFC][PATCH 3/3] ACPI / PM: Avoid resuming devices in ACPI PM domain " Rafael J. Wysocki
2014-05-08 14:59 ` Alan Stern
2014-05-08 19:40 ` Rafael J. Wysocki
2014-05-02 16:12 ` [RFC][PATCH 1/3] PM / sleep: Flags to speed up suspend-resume of runtime-suspended devices Alan Stern
2014-04-24 22:39 ` [RFC][PATCH 2/3][Resend] PM / runtime: Routine for checking device status during system suspend Rafael J. Wysocki
2014-04-25 11:28 ` Ulf Hansson
2014-04-24 22:40 ` [RFC][PATCH 3/3] ACPI / PM: Avoid resuming devices in ACPI PM domain " Rafael J. Wysocki
2014-02-16 23:51 ` [PATCH 2/3][Resend] PM / runtime: Routine for checking device status " Rafael J. Wysocki
2014-02-16 23:52 ` [PATCH 3/3] ACPI / PM: Avoid resuming devices in ACPI PM domain " Rafael J. Wysocki
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