usb_get_descriptor

usb_get_descriptor
Prev	Chapter 5. USB Core APIs	Next

Name

usb_get_descriptor — issues a generic GET_DESCRIPTOR request

Synopsis

`int usb_get_descriptor (`	struct usb_device *	`dev`,
	unsigned char	`type`,
	unsigned char	`index`,
	void *	`buf`,
	int	`size)`;

Arguments

dev: the device whose descriptor is being retrieved
type: the descriptor type (USB_DT_*)
index: the number of the descriptor
buf: where to put the descriptor
size: how big is “buf”?

Context

!in_interrupt ()

Description

Gets a USB descriptor. Convenience functions exist to simplify getting some types of descriptors. Use usb_get_string or usb_string for USB_DT_STRING. Device (USB_DT_DEVICE) and configuration descriptors (USB_DT_CONFIG) are part of the device structure. In addition to a number of USB-standard descriptors, some devices also use class-specific or vendor-specific descriptors.

This call is synchronous, and may not be used in an interrupt context.

Returns the number of bytes received on success, or else the status code returned by the underlying usb_control_msg call.

Prev	Up	Next
usb_sg_cancel	Home	usb_string