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.
If successful, it returns 0, otherwise a negative error number. The
number of actual bytes transferred will be stored in the actual_length
paramater.
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.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 USB_BULK_MSG(9)