USB_SG_INIT(9) USB Core APIs USB_SG_INIT(9)NAMEusb_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
io
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
sg
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
Returns zero for success, else a negative errno value. 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.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 USB_SG_INIT(9)
