On Tue, 13 May 2014 03:10:19 +0200 "Rafael J. Wysocki" <r...@rjwysocki.net> wrote:
> From: Rafael J. Wysocki <rafael.j.wyso...@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 > complete stage of system resume. > > To this end, introduce a new device PM flag, power.direct_complete > and modify the PM core to use that flag as follows. > > If the ->prepare() callback of a device returns a positive number, > the PM core will regard that as an indication that it may leave the > device runtime-suspended. It will then check if the system power > transition in progress is a suspend (and not hibernation in > particular) and if the device is, indeed, runtime-suspended. In that > case, the PM core will set the device's power.direct_complete flag. > Otherwise it will clear power.direct_complete for the device and it > also will later clear it for the device's parent (if there's one). > > Next, the PM core will not invoke the ->suspend() ->suspend_late(), > ->suspend_irq(), ->resume_irq(), ->resume_early(), or ->resume() > callbacks for all devices having power.direct_complete set. It > will invoke their ->complete() callbacks, however, and those > callbacks are then responsible for resuming the devices as > appropriate, if necessary. > > Changelog partly 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.wyso...@intel.com> > --- > drivers/base/power/main.c | 45 > ++++++++++++++++++++++++++++----------------- > include/linux/pm.h | 1 + 2 files changed, 29 insertions(+), > 17 deletions(-) > > Index: linux-pm/include/linux/pm.h > =================================================================== > --- linux-pm.orig/include/linux/pm.h > +++ linux-pm/include/linux/pm.h > @@ -546,6 +546,7 @@ struct dev_pm_info { > bool is_late_suspended:1; > bool ignore_children:1; > bool early_init:1; /* Owned by > the PM core */ > + bool direct_complete:1; /* > Owned by the PM core */ spinlock_t lock; > #ifdef CONFIG_PM_SLEEP > struct list_head entry; > Index: linux-pm/drivers/base/power/main.c > =================================================================== > --- linux-pm.orig/drivers/base/power/main.c > +++ linux-pm/drivers/base/power/main.c > @@ -479,7 +479,7 @@ static int device_resume_noirq(struct de > TRACE_DEVICE(dev); > TRACE_RESUME(0); > > - if (dev->power.syscore) > + if (dev->power.syscore || dev->power.direct_complete) > goto Out; > > if (!dev->power.is_noirq_suspended) > @@ -605,7 +605,7 @@ static int device_resume_early(struct de > TRACE_DEVICE(dev); > TRACE_RESUME(0); > > - if (dev->power.syscore) > + if (dev->power.syscore || dev->power.direct_complete) > goto Out; > > if (!dev->power.is_late_suspended) > @@ -732,7 +732,7 @@ static int device_resume(struct device * > TRACE_DEVICE(dev); > TRACE_RESUME(0); > > - if (dev->power.syscore) > + if (dev->power.syscore || dev->power.direct_complete) > goto Complete; > > dpm_wait(dev->parent, async); > @@ -1007,7 +1007,7 @@ static int __device_suspend_noirq(struct > goto Complete; > } > > - if (dev->power.syscore) > + if (dev->power.syscore || dev->power.direct_complete) > goto Complete; > > dpm_wait_for_children(dev, async); > @@ -1146,7 +1146,7 @@ static int __device_suspend_late(struct > goto Complete; > } > > - if (dev->power.syscore) > + if (dev->power.syscore || dev->power.direct_complete) > goto Complete; > > dpm_wait_for_children(dev, async); > @@ -1312,7 +1312,7 @@ static int __device_suspend(struct devic > > dpm_wait_for_children(dev, async); > > - if (async_error || dev->power.syscore) > + if (async_error || dev->power.syscore || > dev->power.direct_complete) goto Complete; > > dpm_watchdog_set(&wd, dev); > @@ -1365,10 +1365,19 @@ static int __device_suspend(struct devic > > End: > if (!error) { > + struct device *parent = dev->parent; > + > dev->power.is_suspended = true; > - if (dev->power.wakeup_path > - && dev->parent > && !dev->parent->power.ignore_children) > - dev->parent->power.wakeup_path = true; > + if (parent) { > + spin_lock_irq(&parent->power.lock); > + > + dev->parent->power.direct_complete = false; should we respect ignore_children flag here? not all parent devices create children with proper .prepare() function. this allows parents override children. I am looking at USB, a USB device could have logical children such as ep_xx, they don't go through the same subsystem .prepare(). > + if (dev->power.wakeup_path > + && !dev->parent->power.ignore_children) > + dev->parent->power.wakeup_path = > true; + > + spin_unlock_irq(&parent->power.lock); > + } > } > > device_unlock(dev); > @@ -1470,7 +1479,7 @@ static int device_prepare(struct device > { > int (*callback)(struct device *) = NULL; > char *info = NULL; > - int error = 0; > + int ret = 0; > > if (dev->power.syscore) > return 0; > @@ -1518,17 +1527,19 @@ static int device_prepare(struct device > callback = dev->driver->pm->prepare; > } > > - if (callback) { > - error = callback(dev); > - suspend_report_result(callback, error); > - } > + if (callback) > + ret = callback(dev); > > device_unlock(dev); > > - if (error) > + if (ret < 0) { > + suspend_report_result(callback, ret); > pm_runtime_put(dev); > - > - return error; > + return ret; > + } > + dev->power.direct_complete = ret > 0 && state.event == > PM_EVENT_SUSPEND > + && pm_runtime_suspended(dev); > + return 0; > } > > /** > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html [Jacob Pan] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
