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-rw-r--r--Documentation/power/devices.txt67
-rw-r--r--Documentation/power/runtime_pm.txt5
-rw-r--r--Documentation/usb/error-codes.txt9
3 files changed, 22 insertions, 59 deletions
diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index 88880839ece4..64565aac6e40 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -520,59 +520,20 @@ Support for power domains is provided through the pwr_domain field of struct
520device. This field is a pointer to an object of type struct dev_power_domain, 520device. This field is a pointer to an object of type struct dev_power_domain,
521defined in include/linux/pm.h, providing a set of power management callbacks 521defined in include/linux/pm.h, providing a set of power management callbacks
522analogous to the subsystem-level and device driver callbacks that are executed 522analogous to the subsystem-level and device driver callbacks that are executed
523for the given device during all power transitions, in addition to the respective 523for the given device during all power transitions, instead of the respective
524subsystem-level callbacks. Specifically, the power domain "suspend" callbacks 524subsystem-level callbacks. Specifically, if a device's pm_domain pointer is
525(i.e. ->runtime_suspend(), ->suspend(), ->freeze(), ->poweroff(), etc.) are 525not NULL, the ->suspend() callback from the object pointed to by it will be
526executed after the analogous subsystem-level callbacks, while the power domain 526executed instead of its subsystem's (e.g. bus type's) ->suspend() callback and
527"resume" callbacks (i.e. ->runtime_resume(), ->resume(), ->thaw(), ->restore, 527anlogously for all of the remaining callbacks. In other words, power management
528etc.) are executed before the analogous subsystem-level callbacks. Error codes 528domain callbacks, if defined for the given device, always take precedence over
529returned by the "suspend" and "resume" power domain callbacks are ignored. 529the callbacks provided by the device's subsystem (e.g. bus type).
530 530
531Power domain ->runtime_idle() callback is executed before the subsystem-level 531The support for device power management domains is only relevant to platforms
532->runtime_idle() callback and the result returned by it is not ignored. Namely, 532needing to use the same device driver power management callbacks in many
533if it returns error code, the subsystem-level ->runtime_idle() callback will not 533different power domain configurations and wanting to avoid incorporating the
534be called and the helper function rpm_idle() executing it will return error 534support for power domains into subsystem-level callbacks, for example by
535code. This mechanism is intended to help platforms where saving device state 535modifying the platform bus type. Other platforms need not implement it or take
536is a time consuming operation and should only be carried out if all devices 536it into account in any way.
537in the power domain are idle, before turning off the shared power resource(s).
538Namely, the power domain ->runtime_idle() callback may return error code until
539the pm_runtime_idle() helper (or its asychronous version) has been called for
540all devices in the power domain (it is recommended that the returned error code
541be -EBUSY in those cases), preventing the subsystem-level ->runtime_idle()
542callback from being run prematurely.
543
544The support for device power domains is only relevant to platforms needing to
545use the same subsystem-level (e.g. platform bus type) and device driver power
546management callbacks in many different power domain configurations and wanting
547to avoid incorporating the support for power domains into the subsystem-level
548callbacks. The other platforms need not implement it or take it into account
549in any way.
550
551
552System Devices
553--------------
554System devices (sysdevs) follow a slightly different API, which can be found in
555
556 include/linux/sysdev.h
557 drivers/base/sys.c
558
559System devices will be suspended with interrupts disabled, and after all other
560devices have been suspended. On resume, they will be resumed before any other
561devices, and also with interrupts disabled. These things occur in special
562"sysdev_driver" phases, which affect only system devices.
563
564Thus, after the suspend_noirq (or freeze_noirq or poweroff_noirq) phase, when
565the non-boot CPUs are all offline and IRQs are disabled on the remaining online
566CPU, then a sysdev_driver.suspend phase is carried out, and the system enters a
567sleep state (or a system image is created). During resume (or after the image
568has been created or loaded) a sysdev_driver.resume phase is carried out, IRQs
569are enabled on the only online CPU, the non-boot CPUs are enabled, and the
570resume_noirq (or thaw_noirq or restore_noirq) phase begins.
571
572Code to actually enter and exit the system-wide low power state sometimes
573involves hardware details that are only known to the boot firmware, and
574may leave a CPU running software (from SRAM or flash memory) that monitors
575the system and manages its wakeup sequence.
576 537
577 538
578Device Low Power (suspend) States 539Device Low Power (suspend) States
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 654097b130b4..22accb3eb40e 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -566,11 +566,6 @@ to do this is:
566 pm_runtime_set_active(dev); 566 pm_runtime_set_active(dev);
567 pm_runtime_enable(dev); 567 pm_runtime_enable(dev);
568 568
569The PM core always increments the run-time usage counter before calling the
570->prepare() callback and decrements it after calling the ->complete() callback.
571Hence disabling run-time PM temporarily like this will not cause any run-time
572suspend callbacks to be lost.
573
5747. Generic subsystem callbacks 5697. Generic subsystem callbacks
575 570
576Subsystems may wish to conserve code space by using the set of generic power 571Subsystems may wish to conserve code space by using the set of generic power
diff --git a/Documentation/usb/error-codes.txt b/Documentation/usb/error-codes.txt
index d83703ea74b2..b3f606b81a03 100644
--- a/Documentation/usb/error-codes.txt
+++ b/Documentation/usb/error-codes.txt
@@ -76,6 +76,13 @@ A transfer's actual_length may be positive even when an error has been
76reported. That's because transfers often involve several packets, so that 76reported. That's because transfers often involve several packets, so that
77one or more packets could finish before an error stops further endpoint I/O. 77one or more packets could finish before an error stops further endpoint I/O.
78 78
79For isochronous URBs, the urb status value is non-zero only if the URB is
80unlinked, the device is removed, the host controller is disabled, or the total
81transferred length is less than the requested length and the URB_SHORT_NOT_OK
82flag is set. Completion handlers for isochronous URBs should only see
83urb->status set to zero, -ENOENT, -ECONNRESET, -ESHUTDOWN, or -EREMOTEIO.
84Individual frame descriptor status fields may report more status codes.
85
79 86
800 Transfer completed successfully 870 Transfer completed successfully
81 88
@@ -132,7 +139,7 @@ one or more packets could finish before an error stops further endpoint I/O.
132 device removal events immediately. 139 device removal events immediately.
133 140
134-EXDEV ISO transfer only partially completed 141-EXDEV ISO transfer only partially completed
135 look at individual frame status for details 142 (only set in iso_frame_desc[n].status, not urb->status)
136 143
137-EINVAL ISO madness, if this happens: Log off and go home 144-EINVAL ISO madness, if this happens: Log off and go home
138 145