USB_BULK_MSG(9)                           USB Core APIs                           USB_BULK_MSG(9)



NAME
       usb_bulk_msg - Builds a bulk urb, sends it off and waits for completion

SYNOPSIS
       int usb_bulk_msg(struct usb_device * usb_dev, unsigned int pipe, void * data, int len,
                        int * actual_length, int timeout);

ARGUMENTS
       usb_dev
           pointer to the usb device to send the message to

       pipe
           endpoint “pipe” to send the message to

       data
           pointer to the data to send

       len
           length in bytes of the data to send

       actual_length
           pointer to a location to put the actual length transferred in bytes

       timeout
           time in msecs to wait for the message to complete before timing out (if 0 the wait is
           forever)

CONTEXT
       !in_interrupt ()

DESCRIPTION
       This function sends a simple bulk message to a specified endpoint and waits for the
       message to complete, or timeout.

       Don't use this function from within an interrupt context, like a bottom half handler. If
       you need an asynchronous message, or need to send a message from within interrupt context,
       use usb_submit_urb If a thread in your driver uses this call, make sure your disconnect
       method can wait for it to complete. Since you don't have a handle on the URB used, you
       can't cancel the request.

       Because there is no usb_interrupt_msg and no USBDEVFS_INTERRUPT ioctl, users are forced to
       abuse this routine by using it to submit URBs for interrupt endpoints. We will take the
       liberty of creating an interrupt URB (with the default interval) if the target is an
       interrupt endpoint.

RETURN
       If successful, 0. Otherwise a negative error number. The number of actual bytes
       transferred will be stored in the actual_length parameter.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                           USB_BULK_MSG(9)