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usb_set_device_state(9) [centos man page]

USB_SET_DEVICE_STATE(9) 					   USB Core APIs					   USB_SET_DEVICE_STATE(9)

NAME
usb_set_device_state - change a device's current state (usbcore, hcds) SYNOPSIS
void usb_set_device_state(struct usb_device * udev, enum usb_device_state new_state); ARGUMENTS
udev pointer to device whose state should be changed new_state new state value to be stored DESCRIPTION
udev->state is _not_ fully protected by the device lock. Although most transitions are made only while holding the lock, the state can can change to USB_STATE_NOTATTACHED at almost any time. This is so that devices can be marked as disconnected as soon as possible, without having to wait for any semaphores to be released. As a result, all changes to any device's state must be protected by the device_state_lock spinlock. Once a device has been added to the device tree, all changes to its state should be made using this routine. The state should _not_ be set directly. If udev->state is already USB_STATE_NOTATTACHED then no change is made. Otherwise udev->state is set to new_state, and if new_state is USB_STATE_NOTATTACHED then all of udev's descendants' states are also set to USB_STATE_NOTATTACHED. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 USB_SET_DEVICE_STATE(9)

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SYSTEMD.DEVICE(5)						  systemd.device						 SYSTEMD.DEVICE(5)

NAME
systemd.device - systemd device configuration files SYNOPSIS
systemd.device DESCRIPTION
A unit configuration file whose name ends in .device encodes information about a device unit as exposed in the sysfs/udev(7) device tree. This unit type has no specific options. See systemd.unit(5) for the common options of all unit configuration files. The common configuration items are configured in the generic [Unit] and [Install] sections. A separate [Device] section does not exist, since no device-specific options may be configured. systemd will automatically create dynamic device units for all kernel devices that are marked with the "systemd" udev tag (by default all block and network devices, and a few others). This may be used to define dependencies between devices and other units. Device units are named after the /sys and /dev paths they control. Example: the device /dev/sda5 is exposed in systemd as dev-sda5.device. For details about the escaping logic used to convert a file system path to a unit name see systemd.unit(5). THE UDEV DATABASE
The settings of device units may either be configured via unit files, or directly from the udev database (which is recommended). The following udev properties are understood by systemd: SYSTEMD_WANTS= Adds dependencies of type Wants from this unit to all listed units. This may be used to activate arbitrary units, when a specific device becomes available. Note that this and the other tags are not taken into account unless the device is tagged with the "systemd" string in the udev database, because otherwise the device is not exposed as systemd unit. SYSTEMD_ALIAS= Adds an additional alias name to the device unit. This must be an absolute path that is automatically transformed into a unit name. (See above.) SYSTEMD_READY= If set to 0 systemd will consider this device unplugged even if it shows up in the udev tree. If this property is unset or set to 1 the device will be considered plugged the moment it shows up in the udev tree. This property has no influence on the behaviour when a device disappears from the udev tree. This option is useful to support devices that initially show up in an uninitialized state in the tree, and for which a changed event is generated the moment they are fully set up. ID_MODEL_FROM_DATABASE=, ID_MODEL= If set, this property is used as description string for the device unit. SEE ALSO
systemd(1), systemctl(8), systemd.unit(5), udev(7) AUTHOR
Lennart Poettering <lennart@poettering.net> Developer systemd 10/07/2013 SYSTEMD.DEVICE(5)
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