On Wed, Jan 25, 2017 at 08:27:38PM +0800, Lu Baolu wrote: > In my driver, udelay() is mostly used to handle time out. > > Xdbc hides most USB things in its firmware. Early printk driver only needs > to setup the registers/data structures and wait until link ready or time out. > Without udelay(), I have no means to convert the polling times into waiting > time. What is timeout and why? If there is an error other than !ready, I would expect the hardware to inform you of this through another status bit, no? So why can't you poll indefinitely for either ready or error? -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html