Data Structures for Drivers usb_isoc_request(9S)
NAME
usb_isoc_request - USB isochronous request structure
SYNOPSIS
#include
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)DESCRIPTION
A request sent through an isochronous pipe is used to transfer large amounts of packetized data with relative unreliability, but with bounded service periods. A packet is guaranteed to be tried within a bounded time period, but isnot retried upon failure. Isochronous transfers are sup-
ported on both USB 1.1 and USB 2.0 devices. For further information, see section 5.6 of the USB 2.0 specification available at www.usb.org. This section provides information on acceptable combinationsof flags and attributes with additional details. The follow-
ing fields of the usb_isoc_req_t are used to format an iso-
chronous request.usb_frame_number_t
isoc_frame_no; /* frame num to start sending req. */
ushort_t isoc_pkts_count; /* num USB pkts in this request */
/* * The sum of all pkt lengths in an isoc request. Recommend to set it to* zero, so the sum of isoc_pkt_length in the isoc_pkt_descr list will be
* used automatically and no check will be apply to this element. */ushort_t isoc_pkts_length;
ushort_t isoc_error_count;/* num pkts completed w/errs */
usb_req_attrs_t isoc_attributes;/* request-specific attrs */
mblk_t *isoc_data; /* data to xfer */
/* IN or OUT: alloc. by client. */ /* Size=total of all pkt lengths. */usb_opaque_t isoc_client_private; /* for client driver excl use. */
struct usb_isoc_pkt_descr /* (see below) */
*isoc_pkt_descr;
/* * Normal callback function, called upon completion. * This function cannot block as it executes in soft interrupt context. */void (*isoc_cb)(
usb_pipe_handle_t ph, struct usb_isoc_req *req);
/* Exception callback function, for error handling. */SunOS 5.11 Last change: 28 Dec 2006 1
Data Structures for Drivers usb_isoc_request(9S)
void (*isoc_exc_cb)(
usb_pipe_handle_t ph, struct usb_isoc_req *req);
usb_cr_t isoc_completion_reason; /* overall completion status */
/* set by USBA framework *//* See usb_completion_reason(9S) */
usb_cb_flags_t isoc_cb_flags; /* recovery done by callback hndlr */
/* set by USBA on exception. *//* See usb_callback_flags(9S) */
A usb_isoc_pkt_descr_t describes the status of an isochro-
nous packet transferred within a frame or microframe. Thefollowing fields of a usb_isoc_pkt_descr_t packet descriptor
are used within an usb_isoc_req_t. The isoc_pkt_length is
set by the client driver to the amount of data managed by the packet for input or output. The latter two fields are set by the USBA framework to indicate status. Any packetswith an isoc_completion_reason, other than USB_CR_OK, are
reflected in the isoc_error_count of the usb_isoc_req_t.
ushort_t isoc_pkt_length; /* number bytes to transfer */
ushort_t isoc_pkt_actual_length; /* actual number transferred */
usb_cr_t isoc_pkt_status; /* completion status */
If two multi-frame isoc requests that both specify the
USB_ATTRS_ISOC_XFER_ASAP attribute are scheduled closely
together, the first frame of the second request is queued to start after the last frame of the first request.No stalls are seen in isochronous transfer exception call-
backs. Because transfers are not retried upon failure, iso-
chronous transfers continue regardless of errors. Request attributes define special handling for transfers. The following attributes are valid for isochronous requests:USB_ATTRS_ISOC_START_FRAME Start transferring at the
starting frame number speci-
fied in the isoc_frame_no
field of the request.USB_ATTRS_ISOC_XFER_ASAP Start transferring as soon as
possible. The USBA framework picks an immediate frame number to map to the startingSunOS 5.11 Last change: 28 Dec 2006 2
Data Structures for Drivers usb_isoc_request(9S)
frame number.USB_ATTRS_SHORT_XFER_OK Accept transfers where less
data is received than expected.The usb_isoc_req_t contains an array of descriptors that
describe isochronous packets. One isochronous packet is sent per frame or microframe. Because packets that comprise a transfer are sent across consecutive frames or microframes,USB_ATTRS_ONE_XFER is invalid.
See usb_request_attributes(9S) for more information.
Isochronous transfers/requests are subject to the following constraints and caveats:1) The following table indicates combinations of usb_pipe_isoc_xfer
flags argument and fields of the usb_isoc_req_t request argument
(X = don't care). (Note that attributes considered in this tableare ONE_XFER, START_FRAME, XFER_ASAP, and SHORT_XFER, and that
some transfer types are characterized by multiple table entries.) Flags Type Attributes Data Semantics---------------------------------------------------------------
X X X NULL illegalX X ONE_XFER X illegal
X X ISOC_START_FRAME X illegal
& ISOC_XFER_ASAP
X X !ISOC_START_FRAME X illegal
& !ISOC_XFER_ASAP
X OUT SHORT_XFER_OK X illegal
X IN X !=NULL See table note (A)X X ISOC_START_FRAME !=NULL See table note (B)
X X ISOC_XFER_ASAP !=NULL See table note (C)
Table notes: A) continuous polling, new data is returned in cloned request structures via continous callbacks,SunOS 5.11 Last change: 28 Dec 2006 3
Data Structures for Drivers usb_isoc_request(9S)
original request is returned on stop pollingB) invalid if the current_frame number is past
"isoc_frame_no" or "isoc_frame_no" == 0
C)"isoc_frame_no" is ignored. The USBA framework
determines which frame to insert and start the transfer.2) USB_FLAGS_SLEEP indicates to wait for resources but
not for completion. 3) For polled reads: A. The USBA framework accepts a request which specifies the size and number of packets to fill with data. The packets get filled one packet per (1 ms) frame/(125 us) microframe. All requestshave an implicit USB_ATTRS_SHORT_XFER_OK attribute
set, since transfers continue in spite of any en-
countered. The amount of data read per packet willmatch the isoc_pkt_length field of the packet
descriptor unless a short transfer occurs. The actual size is returned in theisoc_pkt_actual_length field of the packet
descriptor. When all packets of the request havebeen processed, a normal callback is done to sig-
nal the completion of the original request. B. When continuous polling is stopped, the original request is returned in an exception callback with acompletion reason of USB_CR_STOPPED_POLLING.
(NOTE: Polling can be restarted from an exception callback corresponding to an original request.Please see usb_pipe_isoc_xfer(9F) for more information.
C. Callbacks must be specified.The isoc_completion_reason indicates the status of the transfer. See
usb_completion_reason(9s) for usb_cr_t definitions.
The isoc_cb_flags are set prior to calling the exception
callback handler to summarize recovery actions taken anderrors encountered during recovery. See usb_callback_flags(9s)
for usb_cb_flags_t definitions.
--- Callback handling ---
All usb request types share the same callback handling. Please seeusb_callback_flags(9s) for a description of use and operation.
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Data Structures for Drivers usb_isoc_request(9S)
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Architecture | PCI-based systems |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| Availability | system/header/header-usb |
|_____________________________|_____________________________|
SEE ALSO
attributes(5), usb_alloc_request(9F),
usb_get_current_frame_number(9F),
usb_get_max_pkts_per_isoc_request(9F),
usb_pipe_bulk_xfer(9F), usb_pipe_ctrl_xfer(9F),
usb_pipe_intr_xfer(9F), usb_pipe_isoc_xfer(9F),
usb_bulk_request(9S), usb_callback_flags(9S),
usb_completion_reason(9S), usb_ctrl_request(9S),
usb_intr_request(9S), usb_request_attributes(9S)
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