PCI/PM: Wrap long lines in documentation

2.4. System-Wide Power Transitions

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There are a few different types of system-wide power transitions, described in

Documentation/driver-api/pm/devices.rst.  Each of them requires devices to be handled

in a specific way and the PM core executes subsystem-level power management

callbacks for this purpose.  They are executed in phases such that each phase

involves executing the same subsystem-level callback for every device belonging

to the given subsystem before the next phase begins.  These phases always run

after tasks have been frozen.

Documentation/driver-api/pm/devices.rst.  Each of them requires devices to be

handled in a specific way and the PM core executes subsystem-level power

management callbacks for this purpose.  They are executed in phases such that

each phase involves executing the same subsystem-level callback for every device

belonging to the given subsystem before the next phase begins.  These phases

always run after tasks have been frozen.

2.4.1. System Suspend

^^^^^^^^^^^^^^^^^^^^^

pre-hibernation memory contents to be restored before the pre-hibernation system

activity can be resumed.

As described in Documentation/driver-api/pm/devices.rst, the hibernation image is loaded

into memory by a fresh instance of the kernel, called the boot kernel, which in

turn is loaded and run by a boot loader in the usual way.  After the boot kernel

has loaded the image, it needs to replace its own code and data with the code

and data of the "hibernated" kernel stored within the image, called the image

kernel.  For this purpose all devices are frozen just like before creating

As described in Documentation/driver-api/pm/devices.rst, the hibernation image

is loaded into memory by a fresh instance of the kernel, called the boot kernel,

which in turn is loaded and run by a boot loader in the usual way.  After the

boot kernel has loaded the image, it needs to replace its own code and data with

the code and data of the "hibernated" kernel stored within the image, called the

image kernel.  For this purpose all devices are frozen just like before creating

the image during hibernation, in the

	prepare, freeze, freeze_noirq

At the time of this writing there are two ways to define power management

callbacks for a PCI device driver, the recommended one, based on using a

dev_pm_ops structure described in Documentation/driver-api/pm/devices.rst, and the

"legacy" one, in which the .suspend(), .suspend_late(), .resume_early(), and

dev_pm_ops structure described in Documentation/driver-api/pm/devices.rst, and

the "legacy" one, in which the .suspend(), .suspend_late(), .resume_early(), and

.resume() callbacks from struct pci_driver are used.  The legacy approach,

however, doesn't allow one to define runtime power management callbacks and is

not really suitable for any new drivers.  Therefore it is not covered by this