USB_INTERFACE

Section: (9)
Updated: 06 August 2003
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NAME

struct usb_interface - what usb device drivers talk to

SYNOPSIS

struct usb_interface {
  /* array of alternate settings for this interface.* these will be in numeric order, 0..num_altsettting*/struct usb_host_interface * altsetting;
  unsigned act_altsetting;
  unsigned num_altsetting;
  int minor;
  struct device dev;
  struct class_device class_dev;
};

MEMBERS

altsetting: array of interface descriptors, one for each alternate setting that may be selected. Each one includes a set of endpoint configurations and will be in numberic order, 0..num_altsetting.
act_altsetting: index of current altsetting. this number is always less than num_altsetting. after the device is configured, each interface uses its default setting of zero.
num_altsetting: number of altsettings defined.
minor: the minor number assigned to this interface, if this interface is bound to a driver that uses the USB major number. If this interface does not use the USB major, this field should be unused. The driver should set this value in the probe function of the driver, after it has been assigned a minor number from the USB core by calling usb_register_dev.
dev: driver model's view of this device
class_dev: driver model's class view of this device.

DESCRIPTION

USB device drivers attach to interfaces on a physical device. Each interface encapsulates a single high level function, such as feeding an audio stream to a speaker or reporting a change in a volume control. Many USB devices only have one interface. The protocol used to talk to an interface's endpoints can be defined in a usb ``class'' specification, or by a product's vendor. The (default) control endpoint is part of every interface, but is never listed among the interface's descriptors.

The driver that is bound to the interface can use standard driver model calls such as dev_get_drvdata on the dev member of this structure.

Each interface may have alternate settings. The initial configuration of a device sets the first of these, but the device driver can change that setting using usb_set_interface. Alternate settings are often used to control the the use of periodic endpoints, such as by having different endpoints use different amounts of reserved USB bandwidth. All standards-conformant USB devices that use isochronous endpoints will use them in non-default settings.

ABOUT THIS DOCUMENT

This documentation was generated with kernel version 2.6.0.

This document was created by man2html, using the manual pages.
Time: 08:41:35 GMT, April 09, 2004