Re: [RFC 1/2] PM: merge drivers/base/power/{main, suspend, resume}.c

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, 31 July 2007 22:48, Alan Stern wrote:
> On Tue, 31 Jul 2007, Rafael J. Wysocki wrote:
> 
> > > Binding and unbinding aren't an issue once the PM core owns all the
> > > device semaphores.
> > 
> > Yes, but currently they aren't held accross the entire suspend.
> 
> Here's my answer to that.  The first patch in this series simply merges 
> several files into one, allowing stuff to be eliminated from the header 
> file and various symbols to be made static.

This is along the lines of what I thought, so I obviously agree with it.

One minor remark below.

> The second patch makes some genuine changes... coming up.
> 
> Alan Stern
> 
> 
> Index: usb-2.6/drivers/base/power/Makefile
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/Makefile
> +++ usb-2.6/drivers/base/power/Makefile
> @@ -1,5 +1,5 @@
>  obj-y			:= shutdown.o
> -obj-$(CONFIG_PM)	+= main.o suspend.o resume.o sysfs.o
> +obj-$(CONFIG_PM)	+= main.o sysfs.o
>  obj-$(CONFIG_PM_TRACE)	+= trace.o

The PM configuration options have been reworked recently, so this needs to
be changed.  Please see http://lkml.org/lkml/2007/7/29/282 and the following
thread (these changes are in current -git w/ some fixes).

>  ifeq ($(CONFIG_DEBUG_DRIVER),y)
> Index: usb-2.6/drivers/base/power/power.h
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/power.h
> +++ usb-2.6/drivers/base/power/power.h
> @@ -11,32 +11,11 @@ extern void device_shutdown(void);
>   * main.c
>   */
>  
> -/*
> - * Used to synchronize global power management operations.
> - */
> -extern struct mutex dpm_mtx;
> -
> -/*
> - * Used to serialize changes to the dpm_* lists.
> - */
> -extern struct mutex dpm_list_mtx;
> -
> -/*
> - * The PM lists.
> - */
> -extern struct list_head dpm_active;
> -extern struct list_head dpm_off;
> -extern struct list_head dpm_off_irq;
> -
> -
> -static inline struct dev_pm_info * to_pm_info(struct list_head * entry)
> -{
> -	return container_of(entry, struct dev_pm_info, entry);
> -}
> +extern struct list_head dpm_active;	/* The active device list */
>  
>  static inline struct device * to_device(struct list_head * entry)
>  {
> -	return container_of(to_pm_info(entry), struct device, power);
> +	return container_of(entry, struct device, power.entry);
>  }
>  
>  extern int device_pm_add(struct device *);
> @@ -49,19 +28,6 @@ extern void device_pm_remove(struct devi
>  extern int dpm_sysfs_add(struct device *);
>  extern void dpm_sysfs_remove(struct device *);
>  
> -/*
> - * resume.c
> - */
> -
> -extern void dpm_resume(void);
> -extern void dpm_power_up(void);
> -extern int resume_device(struct device *);
> -
> -/*
> - * suspend.c
> - */
> -extern int suspend_device(struct device *, pm_message_t);
> -
>  #else /* CONFIG_PM */
>  
>  
> Index: usb-2.6/drivers/base/power/main.c
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/main.c
> +++ usb-2.6/drivers/base/power/main.c
> @@ -20,19 +20,24 @@
>   */
>  
>  #include <linux/device.h>
> +#include <linux/kallsyms.h>
>  #include <linux/mutex.h>
> +#include <linux/pm.h>
> +#include <linux/resume-trace.h>
>  
> +#include "../base.h"
>  #include "power.h"
>  
>  LIST_HEAD(dpm_active);
> -LIST_HEAD(dpm_off);
> -LIST_HEAD(dpm_off_irq);
> +static LIST_HEAD(dpm_off);
> +static LIST_HEAD(dpm_off_irq);
>  
> -DEFINE_MUTEX(dpm_mtx);
> -DEFINE_MUTEX(dpm_list_mtx);
> +static DEFINE_MUTEX(dpm_mtx);
> +static DEFINE_MUTEX(dpm_list_mtx);
>  
>  int (*platform_enable_wakeup)(struct device *dev, int is_on);
>  
> +
>  int device_pm_add(struct device *dev)
>  {
>  	int error;
> @@ -61,3 +66,334 @@ void device_pm_remove(struct device *dev
>  }
>  
>  
> +/*------------------------- Resume routines -------------------------*/
> +
> +/**
> + *	resume_device - Restore state for one device.
> + *	@dev:	Device.
> + *
> + */
> +
> +int resume_device(struct device * dev)
> +{
> +	int error = 0;
> +
> +	TRACE_DEVICE(dev);
> +	TRACE_RESUME(0);
> +
> +	down(&dev->sem);
> +
> +	if (dev->bus && dev->bus->resume) {
> +		dev_dbg(dev,"resuming\n");
> +		error = dev->bus->resume(dev);
> +	}
> +
> +	if (!error && dev->type && dev->type->resume) {
> +		dev_dbg(dev,"resuming\n");
> +		error = dev->type->resume(dev);
> +	}
> +
> +	if (!error && dev->class && dev->class->resume) {
> +		dev_dbg(dev,"class resume\n");
> +		error = dev->class->resume(dev);
> +	}
> +
> +	up(&dev->sem);
> +
> +	TRACE_RESUME(error);
> +	return error;
> +}
> +
> +
> +static int resume_device_early(struct device * dev)
> +{
> +	int error = 0;
> +
> +	TRACE_DEVICE(dev);
> +	TRACE_RESUME(0);
> +	if (dev->bus && dev->bus->resume_early) {
> +		dev_dbg(dev,"EARLY resume\n");
> +		error = dev->bus->resume_early(dev);
> +	}
> +	TRACE_RESUME(error);
> +	return error;
> +}
> +
> +/*
> + * Resume the devices that have either not gone through
> + * the late suspend, or that did go through it but also
> + * went through the early resume
> + */
> +static void dpm_resume(void)
> +{
> +	mutex_lock(&dpm_list_mtx);
> +	while(!list_empty(&dpm_off)) {
> +		struct list_head * entry = dpm_off.next;
> +		struct device * dev = to_device(entry);
> +
> +		get_device(dev);
> +		list_move_tail(entry, &dpm_active);
> +
> +		mutex_unlock(&dpm_list_mtx);
> +		resume_device(dev);
> +		mutex_lock(&dpm_list_mtx);
> +		put_device(dev);
> +	}
> +	mutex_unlock(&dpm_list_mtx);
> +}
> +
> +
> +/**
> + *	device_resume - Restore state of each device in system.
> + *
> + *	Walk the dpm_off list, remove each entry, resume the device,
> + *	then add it to the dpm_active list.
> + */
> +
> +void device_resume(void)
> +{
> +	might_sleep();
> +	mutex_lock(&dpm_mtx);
> +	dpm_resume();
> +	mutex_unlock(&dpm_mtx);
> +}
> +
> +EXPORT_SYMBOL_GPL(device_resume);
> +
> +
> +/**
> + *	dpm_power_up - Power on some devices.
> + *
> + *	Walk the dpm_off_irq list and power each device up. This
> + *	is used for devices that required they be powered down with
> + *	interrupts disabled. As devices are powered on, they are moved
> + *	to the dpm_active list.
> + *
> + *	Interrupts must be disabled when calling this.
> + */
> +
> +static void dpm_power_up(void)
> +{
> +	while(!list_empty(&dpm_off_irq)) {
> +		struct list_head * entry = dpm_off_irq.next;
> +		struct device * dev = to_device(entry);
> +
> +		list_move_tail(entry, &dpm_off);
> +		resume_device_early(dev);
> +	}
> +}
> +
> +
> +/**
> + *	device_power_up - Turn on all devices that need special attention.
> + *
> + *	Power on system devices then devices that required we shut them down
> + *	with interrupts disabled.
> + *	Called with interrupts disabled.
> + */
> +
> +void device_power_up(void)
> +{
> +	sysdev_resume();
> +	dpm_power_up();
> +}
> +
> +EXPORT_SYMBOL_GPL(device_power_up);
> +
> +
> +/*------------------------- Suspend routines -------------------------*/
> +
> +/*
> + * The entries in the dpm_active list are in a depth first order, simply
> + * because children are guaranteed to be discovered after parents, and
> + * are inserted at the back of the list on discovery.
> + *
> + * All list on the suspend path are done in reverse order, so we operate
> + * on the leaves of the device tree (or forests, depending on how you want
> + * to look at it ;) first. As nodes are removed from the back of the list,
> + * they are inserted into the front of their destintation lists.
> + *
> + * Things are the reverse on the resume path - iterations are done in
> + * forward order, and nodes are inserted at the back of their destination
> + * lists. This way, the ancestors will be accessed before their descendents.
> + */
> +
> +static inline char *suspend_verb(u32 event)
> +{
> +	switch (event) {
> +	case PM_EVENT_SUSPEND:	return "suspend";
> +	case PM_EVENT_FREEZE:	return "freeze";
> +	case PM_EVENT_PRETHAW:	return "prethaw";
> +	default:		return "(unknown suspend event)";
> +	}
> +}
> +
> +
> +static void
> +suspend_device_dbg(struct device *dev, pm_message_t state, char *info)
> +{
> +	dev_dbg(dev, "%s%s%s\n", info, suspend_verb(state.event),
> +		((state.event == PM_EVENT_SUSPEND) && device_may_wakeup(dev)) ?
> +		", may wakeup" : "");
> +}
> +
> +/**
> + *	suspend_device - Save state of one device.
> + *	@dev:	Device.
> + *	@state:	Power state device is entering.
> + */
> +
> +int suspend_device(struct device * dev, pm_message_t state)
> +{
> +	int error = 0;
> +
> +	down(&dev->sem);
> +	if (dev->power.power_state.event) {
> +		dev_dbg(dev, "PM: suspend %d-->%d\n",
> +			dev->power.power_state.event, state.event);
> +	}
> +
> +	if (dev->class && dev->class->suspend) {
> +		suspend_device_dbg(dev, state, "class ");
> +		error = dev->class->suspend(dev, state);
> +		suspend_report_result(dev->class->suspend, error);
> +	}
> +
> +	if (!error && dev->type && dev->type->suspend) {
> +		suspend_device_dbg(dev, state, "type ");
> +		error = dev->type->suspend(dev, state);
> +		suspend_report_result(dev->type->suspend, error);
> +	}
> +
> +	if (!error && dev->bus && dev->bus->suspend) {
> +		suspend_device_dbg(dev, state, "");
> +		error = dev->bus->suspend(dev, state);
> +		suspend_report_result(dev->bus->suspend, error);
> +	}
> +	up(&dev->sem);
> +	return error;
> +}
> +
> +
> +/*
> + * This is called with interrupts off, only a single CPU
> + * running. We can't acquire a mutex or semaphore (and we don't
> + * need the protection)
> + */
> +static int suspend_device_late(struct device *dev, pm_message_t state)
> +{
> +	int error = 0;
> +
> +	if (dev->bus && dev->bus->suspend_late) {
> +		suspend_device_dbg(dev, state, "LATE ");
> +		error = dev->bus->suspend_late(dev, state);
> +		suspend_report_result(dev->bus->suspend_late, error);
> +	}
> +	return error;
> +}
> +
> +/**
> + *	device_suspend - Save state and stop all devices in system.
> + *	@state:		Power state to put each device in.
> + *
> + *	Walk the dpm_active list, call ->suspend() for each device, and move
> + *	it to the dpm_off list.
> + *
> + *	(For historical reasons, if it returns -EAGAIN, that used to mean
> + *	that the device would be called again with interrupts disabled.
> + *	These days, we use the "suspend_late()" callback for that, so we
> + *	print a warning and consider it an error).
> + *
> + *	If we get a different error, try and back out.
> + *
> + *	If we hit a failure with any of the devices, call device_resume()
> + *	above to bring the suspended devices back to life.
> + *
> + */
> +
> +int device_suspend(pm_message_t state)
> +{
> +	int error = 0;
> +
> +	might_sleep();
> +	mutex_lock(&dpm_mtx);
> +	mutex_lock(&dpm_list_mtx);
> +	while (!list_empty(&dpm_active) && error == 0) {
> +		struct list_head * entry = dpm_active.prev;
> +		struct device * dev = to_device(entry);
> +
> +		get_device(dev);
> +		mutex_unlock(&dpm_list_mtx);
> +
> +		error = suspend_device(dev, state);
> +
> +		mutex_lock(&dpm_list_mtx);
> +
> +		/* Check if the device got removed */
> +		if (!list_empty(&dev->power.entry)) {
> +			/* Move it to the dpm_off list */
> +			if (!error)
> +				list_move(&dev->power.entry, &dpm_off);
> +		}
> +		if (error)
> +			printk(KERN_ERR "Could not suspend device %s: "
> +				"error %d%s\n",
> +				kobject_name(&dev->kobj), error,
> +				error == -EAGAIN ? " (please convert to suspend_late)" : "");
> +		put_device(dev);
> +	}
> +	mutex_unlock(&dpm_list_mtx);
> +	if (error)
> +		dpm_resume();
> +
> +	mutex_unlock(&dpm_mtx);
> +	return error;
> +}
> +
> +EXPORT_SYMBOL_GPL(device_suspend);
> +
> +/**
> + *	device_power_down - Shut down special devices.
> + *	@state:		Power state to enter.
> + *
> + *	Walk the dpm_off_irq list, calling ->power_down() for each device that
> + *	couldn't power down the device with interrupts enabled. When we're
> + *	done, power down system devices.
> + */
> +
> +int device_power_down(pm_message_t state)
> +{
> +	int error = 0;
> +	struct device * dev;
> +
> +	while (!list_empty(&dpm_off)) {
> +		struct list_head * entry = dpm_off.prev;
> +
> +		dev = to_device(entry);
> +		error = suspend_device_late(dev, state);
> +		if (error)
> +			goto Error;
> +		list_move(&dev->power.entry, &dpm_off_irq);
> +	}
> +
> +	error = sysdev_suspend(state);
> + Done:
> +	return error;
> + Error:
> +	printk(KERN_ERR "Could not power down device %s: "
> +		"error %d\n", kobject_name(&dev->kobj), error);
> +	dpm_power_up();
> +	goto Done;
> +}
> +
> +EXPORT_SYMBOL_GPL(device_power_down);
> +
> +void __suspend_report_result(const char *function, void *fn, int ret)
> +{
> +	if (ret) {
> +		printk(KERN_ERR "%s(): ", function);
> +		print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
> +		printk("%d\n", ret);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(__suspend_report_result);
> Index: usb-2.6/drivers/base/power/resume.c
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/resume.c
> +++ /dev/null
> @@ -1,149 +0,0 @@
> -/*
> - * resume.c - Functions for waking devices up.
> - *
> - * Copyright (c) 2003 Patrick Mochel
> - * Copyright (c) 2003 Open Source Development Labs
> - *
> - * This file is released under the GPLv2
> - *
> - */
> -
> -#include <linux/device.h>
> -#include <linux/resume-trace.h>
> -#include "../base.h"
> -#include "power.h"
> -
> -
> -/**
> - *	resume_device - Restore state for one device.
> - *	@dev:	Device.
> - *
> - */
> -
> -int resume_device(struct device * dev)
> -{
> -	int error = 0;
> -
> -	TRACE_DEVICE(dev);
> -	TRACE_RESUME(0);
> -
> -	down(&dev->sem);
> -
> -	if (dev->bus && dev->bus->resume) {
> -		dev_dbg(dev,"resuming\n");
> -		error = dev->bus->resume(dev);
> -	}
> -
> -	if (!error && dev->type && dev->type->resume) {
> -		dev_dbg(dev,"resuming\n");
> -		error = dev->type->resume(dev);
> -	}
> -
> -	if (!error && dev->class && dev->class->resume) {
> -		dev_dbg(dev,"class resume\n");
> -		error = dev->class->resume(dev);
> -	}
> -
> -	up(&dev->sem);
> -
> -	TRACE_RESUME(error);
> -	return error;
> -}
> -
> -
> -static int resume_device_early(struct device * dev)
> -{
> -	int error = 0;
> -
> -	TRACE_DEVICE(dev);
> -	TRACE_RESUME(0);
> -	if (dev->bus && dev->bus->resume_early) {
> -		dev_dbg(dev,"EARLY resume\n");
> -		error = dev->bus->resume_early(dev);
> -	}
> -	TRACE_RESUME(error);
> -	return error;
> -}
> -
> -/*
> - * Resume the devices that have either not gone through
> - * the late suspend, or that did go through it but also
> - * went through the early resume
> - */
> -void dpm_resume(void)
> -{
> -	mutex_lock(&dpm_list_mtx);
> -	while(!list_empty(&dpm_off)) {
> -		struct list_head * entry = dpm_off.next;
> -		struct device * dev = to_device(entry);
> -
> -		get_device(dev);
> -		list_move_tail(entry, &dpm_active);
> -
> -		mutex_unlock(&dpm_list_mtx);
> -		resume_device(dev);
> -		mutex_lock(&dpm_list_mtx);
> -		put_device(dev);
> -	}
> -	mutex_unlock(&dpm_list_mtx);
> -}
> -
> -
> -/**
> - *	device_resume - Restore state of each device in system.
> - *
> - *	Walk the dpm_off list, remove each entry, resume the device,
> - *	then add it to the dpm_active list.
> - */
> -
> -void device_resume(void)
> -{
> -	might_sleep();
> -	mutex_lock(&dpm_mtx);
> -	dpm_resume();
> -	mutex_unlock(&dpm_mtx);
> -}
> -
> -EXPORT_SYMBOL_GPL(device_resume);
> -
> -
> -/**
> - *	dpm_power_up - Power on some devices.
> - *
> - *	Walk the dpm_off_irq list and power each device up. This
> - *	is used for devices that required they be powered down with
> - *	interrupts disabled. As devices are powered on, they are moved
> - *	to the dpm_active list.
> - *
> - *	Interrupts must be disabled when calling this.
> - */
> -
> -void dpm_power_up(void)
> -{
> -	while(!list_empty(&dpm_off_irq)) {
> -		struct list_head * entry = dpm_off_irq.next;
> -		struct device * dev = to_device(entry);
> -
> -		list_move_tail(entry, &dpm_off);
> -		resume_device_early(dev);
> -	}
> -}
> -
> -
> -/**
> - *	device_power_up - Turn on all devices that need special attention.
> - *
> - *	Power on system devices then devices that required we shut them down
> - *	with interrupts disabled.
> - *	Called with interrupts disabled.
> - */
> -
> -void device_power_up(void)
> -{
> -	sysdev_resume();
> -	dpm_power_up();
> -}
> -
> -EXPORT_SYMBOL_GPL(device_power_up);
> -
> -
> Index: usb-2.6/drivers/base/power/suspend.c
> ===================================================================
> --- usb-2.6.orig/drivers/base/power/suspend.c
> +++ /dev/null
> @@ -1,210 +0,0 @@
> -/*
> - * suspend.c - Functions for putting devices to sleep.
> - *
> - * Copyright (c) 2003 Patrick Mochel
> - * Copyright (c) 2003 Open Source Development Labs
> - *
> - * This file is released under the GPLv2
> - *
> - */
> -
> -#include <linux/device.h>
> -#include <linux/kallsyms.h>
> -#include <linux/pm.h>
> -#include "../base.h"
> -#include "power.h"
> -
> -/*
> - * The entries in the dpm_active list are in a depth first order, simply
> - * because children are guaranteed to be discovered after parents, and
> - * are inserted at the back of the list on discovery.
> - *
> - * All list on the suspend path are done in reverse order, so we operate
> - * on the leaves of the device tree (or forests, depending on how you want
> - * to look at it ;) first. As nodes are removed from the back of the list,
> - * they are inserted into the front of their destintation lists.
> - *
> - * Things are the reverse on the resume path - iterations are done in
> - * forward order, and nodes are inserted at the back of their destination
> - * lists. This way, the ancestors will be accessed before their descendents.
> - */
> -
> -static inline char *suspend_verb(u32 event)
> -{
> -	switch (event) {
> -	case PM_EVENT_SUSPEND:	return "suspend";
> -	case PM_EVENT_FREEZE:	return "freeze";
> -	case PM_EVENT_PRETHAW:	return "prethaw";
> -	default:		return "(unknown suspend event)";
> -	}
> -}
> -
> -
> -static void
> -suspend_device_dbg(struct device *dev, pm_message_t state, char *info)
> -{
> -	dev_dbg(dev, "%s%s%s\n", info, suspend_verb(state.event),
> -		((state.event == PM_EVENT_SUSPEND) && device_may_wakeup(dev)) ?
> -		", may wakeup" : "");
> -}
> -
> -/**
> - *	suspend_device - Save state of one device.
> - *	@dev:	Device.
> - *	@state:	Power state device is entering.
> - */
> -
> -int suspend_device(struct device * dev, pm_message_t state)
> -{
> -	int error = 0;
> -
> -	down(&dev->sem);
> -	if (dev->power.power_state.event) {
> -		dev_dbg(dev, "PM: suspend %d-->%d\n",
> -			dev->power.power_state.event, state.event);
> -	}
> -
> -	if (dev->class && dev->class->suspend) {
> -		suspend_device_dbg(dev, state, "class ");
> -		error = dev->class->suspend(dev, state);
> -		suspend_report_result(dev->class->suspend, error);
> -	}
> -
> -	if (!error && dev->type && dev->type->suspend) {
> -		suspend_device_dbg(dev, state, "type ");
> -		error = dev->type->suspend(dev, state);
> -		suspend_report_result(dev->type->suspend, error);
> -	}
> -
> -	if (!error && dev->bus && dev->bus->suspend) {
> -		suspend_device_dbg(dev, state, "");
> -		error = dev->bus->suspend(dev, state);
> -		suspend_report_result(dev->bus->suspend, error);
> -	}
> -	up(&dev->sem);
> -	return error;
> -}
> -
> -
> -/*
> - * This is called with interrupts off, only a single CPU
> - * running. We can't acquire a mutex or semaphore (and we don't
> - * need the protection)
> - */
> -static int suspend_device_late(struct device *dev, pm_message_t state)
> -{
> -	int error = 0;
> -
> -	if (dev->bus && dev->bus->suspend_late) {
> -		suspend_device_dbg(dev, state, "LATE ");
> -		error = dev->bus->suspend_late(dev, state);
> -		suspend_report_result(dev->bus->suspend_late, error);
> -	}
> -	return error;
> -}
> -
> -/**
> - *	device_suspend - Save state and stop all devices in system.
> - *	@state:		Power state to put each device in.
> - *
> - *	Walk the dpm_active list, call ->suspend() for each device, and move
> - *	it to the dpm_off list.
> - *
> - *	(For historical reasons, if it returns -EAGAIN, that used to mean
> - *	that the device would be called again with interrupts disabled.
> - *	These days, we use the "suspend_late()" callback for that, so we
> - *	print a warning and consider it an error).
> - *
> - *	If we get a different error, try and back out.
> - *
> - *	If we hit a failure with any of the devices, call device_resume()
> - *	above to bring the suspended devices back to life.
> - *
> - */
> -
> -int device_suspend(pm_message_t state)
> -{
> -	int error = 0;
> -
> -	might_sleep();
> -	mutex_lock(&dpm_mtx);
> -	mutex_lock(&dpm_list_mtx);
> -	while (!list_empty(&dpm_active) && error == 0) {
> -		struct list_head * entry = dpm_active.prev;
> -		struct device * dev = to_device(entry);
> -
> -		get_device(dev);
> -		mutex_unlock(&dpm_list_mtx);
> -
> -		error = suspend_device(dev, state);
> -
> -		mutex_lock(&dpm_list_mtx);
> -
> -		/* Check if the device got removed */
> -		if (!list_empty(&dev->power.entry)) {
> -			/* Move it to the dpm_off list */
> -			if (!error)
> -				list_move(&dev->power.entry, &dpm_off);
> -		}
> -		if (error)
> -			printk(KERN_ERR "Could not suspend device %s: "
> -				"error %d%s\n",
> -				kobject_name(&dev->kobj), error,
> -				error == -EAGAIN ? " (please convert to suspend_late)" : "");
> -		put_device(dev);
> -	}
> -	mutex_unlock(&dpm_list_mtx);
> -	if (error)
> -		dpm_resume();
> -
> -	mutex_unlock(&dpm_mtx);
> -	return error;
> -}
> -
> -EXPORT_SYMBOL_GPL(device_suspend);
> -
> -/**
> - *	device_power_down - Shut down special devices.
> - *	@state:		Power state to enter.
> - *
> - *	Walk the dpm_off_irq list, calling ->power_down() for each device that
> - *	couldn't power down the device with interrupts enabled. When we're
> - *	done, power down system devices.
> - */
> -
> -int device_power_down(pm_message_t state)
> -{
> -	int error = 0;
> -	struct device * dev;
> -
> -	while (!list_empty(&dpm_off)) {
> -		struct list_head * entry = dpm_off.prev;
> -
> -		dev = to_device(entry);
> -		error = suspend_device_late(dev, state);
> -		if (error)
> -			goto Error;
> -		list_move(&dev->power.entry, &dpm_off_irq);
> -	}
> -
> -	error = sysdev_suspend(state);
> - Done:
> -	return error;
> - Error:
> -	printk(KERN_ERR "Could not power down device %s: "
> -		"error %d\n", kobject_name(&dev->kobj), error);
> -	dpm_power_up();
> -	goto Done;
> -}
> -
> -EXPORT_SYMBOL_GPL(device_power_down);
> -
> -void __suspend_report_result(const char *function, void *fn, int ret)
> -{
> -	if (ret) {
> -		printk(KERN_ERR "%s(): ", function);
> -		print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
> -		printk("%d\n", ret);
> -	}
> -}
> -EXPORT_SYMBOL_GPL(__suspend_report_result);
> 
> 
> 

-- 
"Premature optimization is the root of all evil." - Donald Knuth