On Thursday, May 08, 2014 12:59:20 PM Ulf Hansson wrote: > On 8 May 2014 12:53, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > > On Thursday, May 08, 2014 09:49:36 AM Ulf Hansson wrote: > >> On 8 May 2014 01:29, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > >> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > >> > > >> > 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@xxxxxxxxx> > >> > --- > >> > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
