usb_sg_init (9) - Linux Manuals

usb_sg_init: initializes scatterlist-based bulk/interrupt I/O request

Command to display usb_sg_init manual in Linux: $ man 9 usb_sg_init

NAME

usb_sg_init - initializes scatterlist-based bulk/interrupt I/O request

SYNOPSIS

int usb_sg_init(struct usb_sg_request * io, struct usb_device * dev, unsigned pipe, unsigned period, struct scatterlist * sg, int nents, size_t length, gfp_t mem_flags);

ARGUMENTS

: request block being initialized. until usb_sg_wait returns, treat this as a pointer to an opaque block of memory,

dev

: the usb device that will send or receive the data

pipe

: endpoint "pipe" used to transfer the data

period

: polling rate for interrupt endpoints, in frames or (for high speed endpoints) microframes; ignored for bulk

: scatterlist entries

nents

: how many entries in the scatterlist

length

: how many bytes to send from the scatterlist, or zero to send every byte identified in the list.

mem_flags

: SLAB_* flags affecting memory allocations in this call

DESCRIPTION

This initializes a scatter/gather request, allocating resources such as I/O mappings and urb memory (except maybe memory used by USB controller drivers).

The request must be issued using usb_sg_wait, which waits for the I/O to complete (or to be canceled) and then cleans up all resources allocated by usb_sg_init.

The request may be canceled with usb_sg_cancel, either before or after usb_sg_wait is called.

RETURN

Zero for success, else a negative errno value.