Question: The EZ-USB General Purpose Driver says that an IOCTL_Ezusb_RESETPIPE call must be made before starting Isochronous read/write operations. Is this due to a quirk in the ezusb.sys driver or a bug in the chip? Also, should there be a delay between the pipe reset and the Isochronous read/write? If so, how long?
Answer: Resetting the pipe before every ISOCHRONOUS transfer is necessary. Due to a quirk in the USB host controller driver (HCD) an ISO pipe must be reset before starting a new transfer. This can be accomplished using IOCTL_Ezusb_RESETPIPE. It is not required to wait after doing a reset to start a read/write using an ISO endpoint.
