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 Kind regards Ulf Hansson -- 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
