usb_control_msg — Builds a control urb, sends it off and waits for completion
int usb_control_msg ( | struct usb_device * | dev, |
| unsigned int | pipe, | |
| __u8 | request, | |
| __u8 | requesttype, | |
| __u16 | value, | |
| __u16 | index, | |
| void * | data, | |
| __u16 | size, | |
| int | timeout); |
devpointer to the usb device to send the message to
pipeendpoint “pipe” to send the message to
requestUSB message request value
requesttypeUSB message request type value
valueUSB message value
indexUSB message index value
datapointer to the data to send
sizelength in bytes of the data to send
timeouttime in msecs to wait for the message to complete before timing out (if 0 the wait is forever)
This function sends a simple control message to a specified endpoint and waits for the message to complete, or timeout.
If successful, it returns the number of bytes transferred, otherwise a negative error number.
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.