Lines Matching +full:wake +full:- +full:on +full:- +full:motion
1 .. _usb-power-management:
7 :Date: Last-updated: February 2014
11 ---------
17 * Changing the default idle-delay time
31 -------------------------
35 component is ``suspended`` it is in a nonfunctional low-power state; it
37 ``resumed`` (returned to a functional full-power state) when the kernel
47 "selective suspend"). This document concentrates mostly on how
59 kernel had been built with ``CONFIG_USB_SUSPEND`` enabled (which depended on
67 ----------------------
76 to resume. This capability goes by several names such as "Wake On
85 --------------------------
89 exact definition depends on the device's driver; drivers are allowed
94 its usbfs file open, whether or not any I/O is going on.
101 -------------------
106 of time, the so-called idle-delay time.
108 Of course, nothing the kernel does on its own initiative should
118 usblp, usblcd, and usb-skeleton (which doesn't count). If a
119 non-supporting driver is bound to a device, the device won't be
134 ---------------------------------
161 This file contains one of two words: ``on`` or ``auto``.
165 - ``on`` means that the device should be resumed and
169 - ``auto`` is the normal state in which the kernel is
181 before the kernel will autosuspend it (the idle-delay
186 idle-delay time.
188 Writing ``-1`` to ``power/autosuspend_delay_ms`` and writing ``on`` to
189 ``power/control`` do essentially the same thing -- they both prevent the
201 Changing the default idle-delay time
202 ------------------------------------
204 The default autosuspend idle-delay time (in seconds) is controlled by
233 then each new USB device will have its autosuspend idle-delay
234 initialized to 5. (The idle-delay values for already existing devices
237 Setting the initial default idle-delay to -1 will prevent any
243 --------
254 ``power/control`` attribute is initialized to ``on``) for all devices other
255 than hubs. Hubs, at least, appear to be reasonably well-behaved in
262 This means that non-hub devices won't be autosuspended unless the user
265 future device managers such as HAL will take on this added
268 also change the idle-delay time; 2 seconds is not the best choice for
280 a number of keyboards show that typing on a suspended keyboard, while
283 of them will issue a remote-wakeup request in response to button
284 presses but not to motion, and some in response to neither.
286 The kernel will not prevent you from enabling autosuspend on devices
293 -----------------------------------------
305 - The ``suspend`` method is called to warn the driver that the
311 - The ``resume`` method is called to tell the driver that the
315 - The ``reset_resume`` method is called to tell the driver that
327 possible to work around the hibernation-forces-disconnect problem by
331 :ref:`usb-persist`) and it can also be used under certain
340 principle one might want to suspend some interfaces on a device (i.e.,
350 ---------------------------------------------------
376 runtime suspend should the interface be bound to a driver again. On
379 has returned -- say from within a work-queue routine -- provided they
395 their non-async counterparts. The big difference is that they
414 set to ``on``, or another interface in the same device might not be
417 carry out the operation automatically when the autosuspend idle-delay
422 autosuspend, there's no idle-delay for an autoresume.
426 -----------------------------------
439 This is exactly the same as writing ``on`` to the ``power/control`` attribute.
444 remote wakeup by typing on it. If the driver sets
445 ``intf->needs_remote_wakeup`` to 1, the kernel won't autosuspend the
460 busy and therefore the next autosuspend idle-delay expiration should
462 so drivers need to worry only when interrupt-driven input arrives.
470 cause autosuspends to fail with -EBUSY if the driver needs to use the
481 ----------------
483 For external events -- but not necessarily for autosuspend or
484 autoresume -- the device semaphore (udev->dev.sem) will be held when a
499 --------------------------------------------
512 Secondly, a dynamic power-management event may occur as a system
515 For example, a suspended device may send a remote-wakeup signal while
520 wakeup may fail and get lost. Which outcome occurs depends on timing
521 and on the hardware and firmware design.
525 ---------------------
552 When a USB 3.0 lpm-capable device is plugged in to a
563 ----------------------
569 In the case of a root or platform-internal hub the host controller
588 As far as the effect on the device itself it is similar to what a device
597 http://dl.dropbox.com/u/96820575/sarah-sharp-lpt-port-power-off2-mini.pdf
601 http://linuxplumbers.ubicast.tv/videos/usb-port-power-off-kerneluserspace-api/
608 power control implementation will block poweroff attempts on that
613 -------------------------------------
620 suspended. This mechanism is dependent on the hub advertising port power
631 lost and all attached child-devices will disconnect. A good rule of thumb is
639 prefix=/sys/devices/pci0000:00/0000:00:14.0/usb3/3-1
645 $prefix/3-1:1.0/3-1-port1/device
647 $prefix/3-1:1.0/3-1-port1/power/pm_qos_no_power_off
648 $prefix/3-1:1.0/3-1-port1/device/power/control
649 $prefix/3-1:1.0/3-1-port1/device/3-1.1:<intf0>/driver/unbind
650 $prefix/3-1:1.0/3-1-port1/device/3-1.1:<intf1>/driver/unbind
652 $prefix/3-1:1.0/3-1-port1/device/3-1.1:<intfN>/driver/unbind
654 In addition to these files some ports may have a 'peer' link to a port on
656 hi-speed peer::
658 $prefix/3-1:1.0/3-1-port1/peer -> ../../../../usb2/2-1/2-1:1.0/2-1-port1
659 ../../../../usb2/2-1/2-1:1.0/2-1-port1/peer -> ../../../../usb3/3-1/3-1:1.0/3-1-port1
662 peer ports are simply the hi-speed and superspeed interface pins that
667 connection and attempt to connect to the hi-speed pins. The
670 1. Port suspend is sequenced to guarantee that hi-speed ports are powered-off
671 before their superspeed peer is permitted to power-off. The implication is
672 that the setting ``pm_qos_no_power_off`` to zero on a superspeed port may
673 not cause the port to power-off until its highspeed peer has gone to its
675 if it wants to guarantee that a superspeed port will power-off.
677 2. Port resume is sequenced to force a superspeed port to power-on prior to its
684 child device can suspend (autosuspend-delay) and resume (reset-resume
689 ``<hubdev-portX>/power/pm_qos_no_power_off``:
697 ``<hubdev-portX>/power/runtime_status``:
698 This file reflects whether the port is 'active' (power is on)
702 ``<hubdev-portX>/connect_type``:
703 An advisory read-only flag to userspace indicating the
710 port on the platform. Typically userspace would choose
728 exposed on a platform. Considered safe to be
729 powered-off at all times.
738 - since we are relying on the BIOS to get this ACPI
742 - Take care in clearing ``pm_qos_no_power_off``. Once
758 power session loss (suspend / port-power event). When
764 this time the only mechanism to clear the usb-internal
765 wakeup-capability for an interface device is to unbind
768 Summary of poweroff pre-requisite settings relative to a port device::
777 -------------------------------------
793 all ports (set ``<hubdev-portX>/power/pm_qos_no_power_off`` to ``0``) when
796 ports when the screen blanks, and re-power them when the screen becomes