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


usb_pipe_intr_xfer, usb_pipe_stop_intr_polling - USB interrupt transfer
and polling functions


#include <sys/usb/usba.h>

int usb_pipe_intr_xfer(usb_pipe_handle_t pipe_handle, usb_intr_req_t *request,
usb_flags_t flags);

void usb_pipe_stop_intr_polling(usb_pipe_handle_t pipe_handle, usb__flags_t flags);


illumos DDI specific (illumos DDI)


For usb_pipe_intr_xfer():

Interrupt pipe handle on which request is made.

Pointer to interrupt transfer request.

USB_FLAGS_SLEEP is the only flag recognized. Wait for
needed resources if unavailable. For requests specifying
the USB_ATTRS_ONE_XFER attribute, wait for the request to

For usb_pipe_stop_intr_polling():

Interrupt pipe handle on which to stop polling for data.

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


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

There are three categories of interrupt transfers: periodic or polled
interrupt-IN, single-transfer interrupt-IN, and (single-transfer)

Periodic Interrupt-IN Transfers
Periodic or polled interrupt-IN transfers execute on input requests which
do not have the USB_ATTRS_ONE_XFER attribute set. One request enables
repetitive transfers at a periodic rate set by the endpoint's bInterval.
There can be only one interrupt-IN request submitted at a time.

Periodic interrupt-IN transfers are always asynchronous. Client driver
notification of new data is always via a callback. The USB_FLAGS_SLEEP
flag is only to wait for resources to become available. Callbacks must
always be in place to receive transfer completion notification. Please
see usb_callback_flags(9S) for details on USB callbacks.

Calls made to usb_pipe_intr_xfer() for starting input polling need
allocate only one request. The USBA framework allocates a new request
each time polling has new data to return. (Note that each request
returned must be freed via usb_free_intr_req(9F). Specify a zero length
when calling usb_alloc_intr_req() to allocate the original request, since
it will not be used to return data. Set the intr_len in the request to
specify how much data can be returned per polling interval.

The original request passed to usb_pipe_intr_xfer() is used to return
status when polling is terminated, or on an error condition when the
USB_ATTRS_AUTOCLEARING attribute is set for the request. If autoclearing
is not set, the current (non-original) request is returned on error. Call
usb_pipe_reset(9F) to reset the pipe and get back the original request in
this case. The USB_CR_STOPPED_POLLING flag is always set for callbacks
where the original request is returned.

Single-transfer Interrupt-IN Transfers
Interrupt-IN requests which have the USB_ATTRS_ONE_XFER attribute perform
a single transfer. Such requests are synchronous when the USB_FLAGS_SLEEP
flag is specified. Calls for synchronous requests do not return until
their transaction is complete, and their callbacks are optional. The
request is returned to the client through the normal or the exception
completion callback to signal either normal completion or an error

Interrupt-OUT Transfers
Interrupt-OUT requests always set up for a single transfer. However,
multiple requests can be queued and execute in periodic fashion until

Interrupt-OUT transfers are synchronous when the USB_FLAGS_SLEEP flag is
set in the request's flags. Calls for synchronous transfers will not
return until their transaction has completed. Calls for asynchronous
transfers notify the client driver of transaction completion via a normal
callback, or error completion via an exception callback.

The usb_pipe_stop_intr_polling() function terminates polling on
interrupt-IN pipes and 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.

The client driver may restart polling from an exception callback only if
the callback corresponds to an original request. The callback handler
checks for the following completion reasons to ensure that a callback
corresponds to an original request:


The callback handler also checks the request's intr_data field to mark
original polling requests, when the requests are created with a zero len
argument. In this case, a NULL intr_data field distinguishes a returned
original request from a request allocated by the framework during

Mblks for data for interrupt-OUT requests are allocated when a request is
allocated via usb_alloc_intr_req(9F) by passing a non-negative value for
the len argument.


For usb_pipe_intr_xfer()

Transfer was successful.

Request is NULL.

Called from interrupt context with the

The request has been freed or otherwise

A set of conflicting attributes was specified.
See usb_intr_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 interrupt request was specified with a NULL
data and a non-zero intr_len value.

An IN interrupt request was specified with both
polling (USB_ATTRS_ONE_XFER clear in attributes)
and non-zero timeout specified.

An IN interrupt request was specified with a
non-NULL data argument.

An OUT interrupt request was specified with a
NULL data argument.

Pipe handle is NULL or invalid.

Pipe is closing or closed.

Pipe handle refers to a pipe which is in the

Memory, descriptors or other resources

Host controller is in error state.

An asynchronous transfer failed or an internal
error occurred.

An intr polling request is made while polling is
already in progress.

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

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

For usb_pipe_stop_intr_polling()

None, but fails if called with USB_FLAGS_SLEEP specified from interrupt
context, pipe handle is invalid, NULL or pertains to a closing or closed
pipe, or the pipe is in an error state. Error messages are logged to the
console logfile.

Exception handlers' queued requests which are flushed by these commands
before execution are returned with completion reason of USB_CR_FLUSHED.


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


/* Start polling on interrupt-IN pipe. */

usb_intr_req_t intr_req;
void intr_pipe_callback(usb_pipe_handle_t, usb_intr_req_t*);
void intr_pipe_exception_callback(
usb_pipe_handle_t, usb_intr_req_t*);
usb_ep_descr_t *ep_descr;

ep_descr = ...;
intr_req = usb_alloc_intr_req(dip, 0, USB_FLAGS_SLEEP);
intr_req->intr_attributes = USB_ATTRS_SHORT_XFER_OK;
intr_req->intr_len = ep_descr->wMaxPacketSize;
intr_req->intr_cb = intr_pipe_callback;
intr_req->intr_exc_cb = intr_pipe_exception_callback;

if ((rval = usb_pipe_intr_xfer(pipe, intr_req, USB_FLAGS_NOSLEEP))
cmn_err (CE_WARN, "%s%d: Error starting interrupt pipe polling.",
ddi_driver_name(dip), ddi_get_instance(dip));


/* Stop polling before setting device idle. Wait for polling to stop. */

usb_pipe_stop_intr_polling(pipe, USB_FLAGS_SLEEP);
(void) pm_idle_component(dip, 0);


/* Allocate, initialize and issue a synchronous intr-OUT request. */

usb_intr_req_t intr_req;
mblk_t *mblk;
usb_ep_descr_t *ep_descr;

ep_descr = ...;

intr_req =
usb_alloc_intr_req(dip, ep_descr->wMaxPacketSize, USB_FLAGS_SLEEP);

intr_req->intr_attributes = USB_ATTRS_AUTOCLEARING;
mblk = intr_req->intr_data;
bcopy(buffer, mblk->b_wptr, ep_descr->wMaxPacketSize);
mblk->b_wptr += ep_descr->wMaxPacketSize;

if ((rval = usb_pipe_intr_xfer(pipe, intr_req, USB_FLAGS_SLEEP))
cmn_err (CE_WARN, "%s%d: Error writing intr data.",
ddi_driver_name(dip), ddi_get_instance(dip));


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

|Architecture | PCI-based systems |
|Interface stability | Evolving |


attributes(7), usb_alloc_request(9F), usb_get_cfg(9F),
usb_get_status(9F), usb_pipe_bulk_xfer(9F), usb_pipe_ctrl_xfer(9F),
usb_pipe_get_state(9F), usb_pipe_isoc_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_INTR_XFER(9F)