On Wednesday, May 14, 2014 03:24:21 PM Jacob Pan wrote: > On Tue, 13 May 2014 03:10:19 +0200 > "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 > > 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.wysocki@xxxxxxxxx> > > --- > > 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(). Well, I'm not sure about that. Let me consider that for a while. Alan, what do you think? > > > + 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; > > } > > > > /** > > > > -- Rafael -- 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
