USB_PIPE_ISOC_XFER(9F) Kernel Functions for Drivers USB_PIPE_ISOC_XFER(9F)

NAME


usb_pipe_isoc_xfer, usb_pipe_stop_isoc_polling - USB isochronous transfer
and polling functions

SYNOPSIS


#include <sys/usb/usba.h>


int usb_pipe_isoc_xfer(usb_pipe_handle_t pipe_handle, usb_isoc_req_t *request,
usb_flags_t flags);


void usb_pipe_stop_isoc_polling(usb_pipe_handle_t pipe_handle, usb__flags_t flags);


INTERFACE LEVEL


illumos DDI specific (illumos DDI)

PARAMETERS


For usb_pipe_isoc_xfer():

pipe_handle
Isochronous pipe handle on which request is made.


request
Pointer to isochronous transfer request.


flags
USB_FLAGS_SLEEP is the only flag recognized. Wait for
needed resources if unavailable.


For usb_pipe_stop_isoc_polling():

pipe_handle
Isochronous pipe handle on which to stop polling for
input.


flags
USB_FLAGS_SLEEP is the only flag recognized. Wait for
polling to stop.


DESCRIPTION


The usb_pipe_isoc_xfer() function requests the USBA framework to perform
a transfer through a USB isochronous pipe. The request is passed to
the host controller driver (HCD), which performs the necessary
transactions to complete the request.


By their nature, isochronous transfers require several transactions for
completion. Each request may contain several packet descriptors.
Descriptors correspond to subtransfers to be made in different frames. A
request is deemed completed once all packets of that request have been
processed. It is illegal to specify the USB_ATTRS_ONE_XFER attribute in
an isochronous request. The isochronous polling interval is always one
millisecond, the period of a full-speed frame.


All isochronous requests are asynchronous, and will notify the caller of
their completion via a callback function. All isochronous requests must
specify normal and exception callback handlers.


Requests will wait for needed, unavailable resources when USB_FLAGS_SLEEP
has been specified in flags. Requests made without USB_FLAGS_SLEEP set
will fail if needed resources are not readily available.


No errors seen during request processing will result in aborted transfers
or exception callbacks. Such errors will instead be logged in the packet
descriptor's isoc_pkt_status field. These errors can be examined when the
completed request is returned through a normal callback.

Isochronous-OUT TRANSFERS
Allocate room for data when allocating isochronous-OUT requests via
usb_alloc_isoc_req(9F), by passing a positive value for the len
argument. The data will be divided among the request transactions, each
transaction represented by a packet descriptor. (See
usb_isoc_request(9S). When all of the data has been sent, regardless of
any errors encountered, a normal transfer callback will be made to
notify the client driver of completion.


If a request is submitted while other requests are active or queued, and
the new request has its USB_ATTRS_ISOC_XFER_ASAP attribute set, the host
controller driver will queue the request to start on a frame which
immediately follows the last frame of the last queued request.

Isochronous-IN TRANSFERS
All isochronous-IN transfers start background polling, and require only a
single (original) request. The USBA framework will allocate a new
request each time polling has new data to return. Specify a zero length
when calling usb_alloc_isoc_req() to allocate the original request, since
it will not be used to return data. Set the isoc_pkts_length in the
request to specify how much data to poll per interval (the length of one
packet in the request).


The original request passed to usb_pipe_isoc_xfer() will be used to
return status when polling termination is requested, or for error
condition notification. There can be only one isochronous-IN request
submitted at a time.

CALLBACKS


Isochronous transfer normal-completion callbacks cannot block for any
reason since they are called from interrupt context. They will have
USB_CB_INTR_CONTEXT set in their callback flags to note this.


Isochronous exception callbacks have the following restrictions for
blocking:

1. They can block for resources (for example to allocate memory).

2. They cannot block for synchronous completion of a command (for
example usb_pipe_close(9F)) done on the same pipe.
Asynchronous commands can be started, when the pipe's policy
pp_max_async_reqs field is initialized to accommodate them.

3. They cannot block waiting for another callback to complete.

4.
They cannot block waiting for a synchronous transfer request
to complete. They can, however, make an asynchronous request
(such as restarting polling with a new isochronous-IN
transfer).


Please see the section on callbacks in usb_callback_flags(9S) for more
information.


All isochronous transfer exception callbacks signify that polling has
stopped. Polling requests are returned with the following completion
reasons:

USB_CR_STOPPED_POLLING
USB_CR_PIPE_CLOSING


Note: There are no exception callbacks for error conditions.


The usb_pipe_stop_isoc_polling() function terminates polling on an
isochronous-IN pipe. The usb_pipe_stop_isoc_polling() function does the
following:

1. Cease polling.

2. Allow any requests-in-progress to complete and be returned to
the client driver through the normal callback mechanism.

3. Idle the pipe.

4. Return the original polling request to the client driver
through an exception callback with a completion reason of
USB_CR_STOPPED_POLLING.

RETURN VALUES


For usb_pipe_isoc_xfer():

USB_SUCCESS
Transfer was successful.


USB_INVALID_ARGS
Request is NULL.


USB_INVALID_CONTEXT
Called from interrupt context with the
USB_FLAGS_SLEEP flag set.


USB_INVALID_REQUEST
The request has been freed or otherwise
invalidated.

A set of conflicting attributes were
specified. See usb_isoc_request(9S).

The normal and/or exception callback was
NULL, USB_FLAGS_SLEEP was not set and
USB_ATTRS_ONE_XFER was not set.

An isochronous request was specified with a
zeroed isoc_pkt_descr, a NULL isoc_pkt_descr,
or a NULL data argument.

An isochronous request was specified with
USB_ATTRS_ISOC_XFER_ASAP and a nonzero
isoc_frame_no.


USB_NO_FRAME_NUMBER
An isochronous request was not specified with
one and only one of
USB_ATTRS_ISOC_START_FRAME or
USB_ATTRS_ISOC_XFER_ASAP specified.

An isochronous request was specified with
USB_ATTRS_ISOC_START_FRAME and a zero
isoc_frame_no.


USB_INVALID_START_FRAME
An isochronous request was specified with an
invalid starting frame number (less than
current frame number, or zero) and
USB_ATTRS_ISOC_START_FRAME specified.


USB_INVALID_PIPE
Pipe handle is NULL or invalid.

Pipe is closing or closed.


USB_PIPE_ERROR
Pipe handle refers to a pipe which is in the
USB_PIPE_STATE_ERROR state.


USB_NO_RESOURCES
Memory, descriptors or other resources
unavailable.


USB_HC_HARDWARE_ERROR
Host controller is in error state.


USB_FAILURE
An asynchronous transfer failed or an internal
error occurred.

An isoch request requested too much data:
(length > (usb_get_max_pkts_per_isoc_request() *
endpoint's wMaxPacketSize))

The pipe is in an unsuitable state (error,
busy, not ready).


Additional status information may be available in the
isoc_completion_reason and isoc_cb_flags fields of the request. Please
see usb_completion_reason(9S) and usb_callback_flags(9S) for more
information.


For usb_pipe_stop_isoc_polling():


None, but will fail if called with USB_FLAGS_SLEEP specified from
interrupt context; the pipe handle is invalid, NULL or pertains to a
closing or closed pipe; or the pipe is in an error state. Messages
regarding these errors will be logged to the console logfile.

CONTEXT


Both of these functions may be called from kernel or user context without
regard to arguments. May be called from interrupt context only when the
USB_FLAGS_SLEEP flag is clear.

EXAMPLES


/* Start polling on an isochronous-IN pipe. */

usb_isoc_req_t isoc_req;
void isoc_pipe_callback(usb_pipe_handle_t, usb_isoc_req_t*);
void isoc_pipe_exception_callback(
usb_pipe_handle_t, usb_isoc_req_t*);
uint_t pkt_size;
usb_ep_data_t *isoc_ep_tree_node;
usb_ep_descr_t *isoc_ep_descr = ...; /* From usb_lookup_ep_data() */

isoc_ep_descr = &isoc_ep_tree_node->ep_descr;
pkt_size = isoc_ep_descr->wMaxPacketSize;

isoc_req = usb_alloc_isoc_req(
dip, num_pkts, NUM_PKTS * pkt_size, USB_FLAGS_SLEEP);
...
...
isoc_req->isoc_attributes = USB_ATTRS_ISOC_XFER_ASAP;
...
...
isoc_req->isoc_cb = isoc_pipe_callback;
isoc_req->isoc_exc_cb = isoc_pipe_exception_callback;
...
...
isoc_req->isoc_pkts_length = pkt_size;
isoc_req->isoc_pkts_count = NUM_PKTS;
for (pkt = 0; pkt < NUM_PKTS; pkt++) {
isoc_req->isoc_pkt_descr[pkt].isoc_pkt_length = pkt_size;
}

if ((rval = usb_pipe_isoc_xfer(pipe, isoc_req, USB_FLAGS_NOSLEEP))
!= USB_SUCCESS) {
cmn_err (CE_WARN,"%s%d: Error starting isochronous pipe polling.",
ddi_driver_name(dip), ddi_get_instance(dip));
}

-------

/* Stop polling before powering off device. Wait for polling to stop. */

usb_pipe_stop_isoc_polling(pipe, USB_FLAGS_SLEEP);
pm_idle_component(dip, 0);


ATTRIBUTES


See attributes(7) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Architecture | PCI-based systems |
+--------------------+-------------------+
|Interface stability | Evolving |
+--------------------+-------------------+

SEE ALSO


attributes(7), usb_alloc_request(9F), usb_get_cfg(9F),
usb_get_current_frame_number(9F), usb_get_max_pkts_per_isoc_request(9F),
usb_get_status(9F), usb_pipe_bulk_xfer(9F), usb_pipe_ctrl_xfer(9F),
usb_pipe_get_state(9F), usb_pipe_intr_xfer(9F), usb_pipe_reset(9F),
usb_pipe_xopen(9F), usb_bulk_request(9S), usb_callback_flags(9S),
usb_completion_reason(9S), usb_ctrl_request(9S), usb_ep_descr(9S),
usb_intr_request(9S), usb_isoc_request(9S)

illumos September 16, 2016 USB_PIPE_ISOC_XFER(9F)