usb_get_current_frame_numKernel)Functions for usb_get_current_frame_number(9F)NAMEusb_get_current_frame_number - Return current logical usb frame number
SYNOPSIS
#include <sys/usb/usba.h>
usb_frame_number_t usb_get_current_frame_number(dev_info_t *dip);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)
PARAMETERS
dip
Pointer to the device's dev_info structure.
DESCRIPTION
The usb_get_current_frame_number() function retrieves the current logi‐
cal USB frame number.
Isochronous requests can be started on a particular numbered frame. An
offset number of frames (typically between 4 and 10) can be added to
the current logical frame number to specify the number of an upcoming
frame to start an isochronous request.
The USB specification requires that the frame frequency (the period
between start-of-frame packets) is one millisecond. The Solaris oper‐
ating environment USB implementation uses a running counter of the num‐
ber of milliseconds since boot as the current logical frame number.
RETURN VALUES
On success, the usb_get_current_frame_number() function returns the
current USB frame number. On failure it returns 0. The function fails
if dip is NULL.
CONTEXT
May be called from user, kernel or interrupt context.
EXAMPLES
usb_pipe_handle_t handle;
usb_frame_number_t offset = 10;
usb_isoc_req_t *isoc_req;
isoc_req = usb_alloc_isoc_req(...);
...
...
isoc_req->isoc_frame_no = usb_get_current_frame_number(dip) + offset;
isoc_req->isoc_attributes = USB_ATTRS_ISOC_START_FRAME;
...
...
if (usb_pipe_isoc_xfer(handle, isoc_req, 0) != USB_SUCCESS) {
...
}
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Architecture │PCI-based systems │
├─────────────────────────────┼─────────────────────────────┤
│Interface stability │Evolving │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWusb │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOattributes(5), usb_alloc_isoc_req(9F),
usb_get_max_pkts_per_isoc_request(9F), usb_pipe_isoc_xfer(9F),
usb_pipe_get_max_bulk_transfer_size(9F), usb_isoc_request(9S)SunOS 5.10 25 July 2004 usb_get_current_frame_number(9F)
