Pipes are in one of the following states:
USB_PIPE_STATE_IDLE
All control and bulk pipes, interrupt-OUT pipes, and isochronous-OUT pipes: No request is in progress.
Interrupt-IN and isochronous-IN pipes: No polling is in progress.
USB_PIPE_STATE_ACTIVE
All control and bulk pipes, interrupt-OUT pipes, and isochronous-OUT pipes: The pipe is transferring data or an I/O request is active.
Interrupt-IN and isochronous-IN pipes: Polling is active.
USB_PIPE_STATE_ERROR. An error occurred. If this pipe is not the default pipe and if autoclearing is not enabled, then the client driver must call the usb_pipe_reset(9F) function.
USB_PIPE_STATE_CLOSING. The pipe is being closed.
USB_PIPE_STATE_CLOSED. The pipe is closed.
Call the usb_pipe_get_state(9F) function to retrieve the state of a pipe.