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142 lines
4.9 KiB
142 lines
4.9 KiB
What: /sys/bus/usb/devices/.../power/persist |
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Date: May 2007 |
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KernelVersion: 2.6.23 |
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Contact: Alan Stern <[email protected]> |
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Description: |
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USB device directories can contain a file named power/persist. |
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The file holds a boolean value (0 or 1) indicating whether or |
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not the "USB-Persist" facility is enabled for the device. For |
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hubs this facility is always enabled and their device |
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directories will not contain this file. |
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For more information, see Documentation/driver-api/usb/persist.rst. |
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What: /sys/bus/usb/devices/.../power/autosuspend |
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Date: March 2007 |
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KernelVersion: 2.6.21 |
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Contact: Alan Stern <[email protected]> |
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Description: |
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Each USB device directory will contain a file named |
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power/autosuspend. This file holds the time (in seconds) |
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the device must be idle before it will be autosuspended. |
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0 means the device will be autosuspended as soon as |
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possible. Negative values will prevent the device from |
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being autosuspended at all, and writing a negative value |
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will resume the device if it is already suspended. |
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The autosuspend delay for newly-created devices is set to |
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the value of the usbcore.autosuspend module parameter. |
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What: /sys/bus/usb/device/.../power/connected_duration |
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Date: January 2008 |
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KernelVersion: 2.6.25 |
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Contact: Sarah Sharp <[email protected]> |
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Description: |
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If CONFIG_PM is enabled, then this file is present. When read, |
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it returns the total time (in msec) that the USB device has been |
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connected to the machine. This file is read-only. |
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Users: |
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PowerTOP <[email protected]> |
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https://01.org/powertop/ |
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What: /sys/bus/usb/device/.../power/active_duration |
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Date: January 2008 |
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KernelVersion: 2.6.25 |
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Contact: Sarah Sharp <[email protected]> |
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Description: |
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If CONFIG_PM is enabled, then this file is present. When read, |
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it returns the total time (in msec) that the USB device has been |
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active, i.e. not in a suspended state. This file is read-only. |
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Tools can use this file and the connected_duration file to |
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compute the percentage of time that a device has been active. |
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For example:: |
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echo $((100 * `cat active_duration` / `cat connected_duration`)) |
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will give an integer percentage. Note that this does not |
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account for counter wrap. |
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Users: |
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PowerTOP <[email protected]> |
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https://01.org/powertop/ |
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What: /sys/bus/usb/devices/<busnum>-<port[.port]>...:<config num>-<interface num>/supports_autosuspend |
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Date: January 2008 |
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KernelVersion: 2.6.27 |
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Contact: Sarah Sharp <[email protected]> |
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Description: |
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When read, this file returns 1 if the interface driver |
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for this interface supports autosuspend. It also |
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returns 1 if no driver has claimed this interface, as an |
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unclaimed interface will not stop the device from being |
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autosuspended if all other interface drivers are idle. |
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The file returns 0 if autosuspend support has not been |
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added to the driver. |
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Users: |
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USB PM tool |
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git://git.moblin.org/users/sarah/usb-pm-tool/ |
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What: /sys/bus/usb/device/.../avoid_reset_quirk |
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Date: December 2009 |
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Contact: Oliver Neukum <[email protected]> |
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Description: |
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Writing 1 to this file tells the kernel that this |
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device will morph into another mode when it is reset. |
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Drivers will not use reset for error handling for |
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such devices. |
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Users: |
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usb_modeswitch |
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What: /sys/bus/usb/devices/.../devnum |
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KernelVersion: since at least 2.6.18 |
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Description: |
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Device address on the USB bus. |
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Users: |
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libusb |
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What: /sys/bus/usb/devices/.../bConfigurationValue |
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KernelVersion: since at least 2.6.18 |
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Description: |
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bConfigurationValue of the *active* configuration for the |
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device. Writing 0 or -1 to bConfigurationValue will reset the |
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active configuration (unconfigure the device). Writing |
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another value will change the active configuration. |
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Note that some devices, in violation of the USB spec, have a |
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configuration with a value equal to 0. Writing 0 to |
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bConfigurationValue for these devices will install that |
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configuration, rather then unconfigure the device. |
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Writing -1 will always unconfigure the device. |
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Users: |
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libusb |
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What: /sys/bus/usb/devices/.../busnum |
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KernelVersion: 2.6.22 |
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Description: |
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Bus-number of the USB-bus the device is connected to. |
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Users: |
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libusb |
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What: /sys/bus/usb/devices/.../descriptors |
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KernelVersion: 2.6.26 |
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Description: |
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Binary file containing cached descriptors of the device. The |
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binary data consists of the device descriptor followed by the |
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descriptors for each configuration of the device. |
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Note that the wTotalLength of the config descriptors can not |
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be trusted, as the device may have a smaller config descriptor |
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than it advertises. The bLength field of each (sub) descriptor |
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can be trusted, and can be used to seek forward one (sub) |
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descriptor at a time until the next config descriptor is found. |
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All descriptors read from this file are in bus-endian format |
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Users: |
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libusb |
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What: /sys/bus/usb/devices/.../speed |
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KernelVersion: since at least 2.6.18 |
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Description: |
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Speed the device is connected with to the usb-host in |
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Mbit / second. IE one of 1.5 / 12 / 480 / 5000. |
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Users: |
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libusb
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