Hi, From the ehci-hub.c, I find that ehci_bus_suspend/resume have some code like this: if (time_before(jiffies, ehci->netx_statechange)) msleep(5); ... ehci->next_statechange = jiffies + msec_to_jiffies(10); and if (time_before(jiffies, ehci->netx_statechange)) msleep(5); ... ehci->next_statechange = jiffies + msec_to_jiffies(5); but I don't know why such a short sleep is needed, and why one is [ehci->next_statechange = jiffies + msec_to_jiffies(10)] and the other is [ehci->next_statechange = jiffies + msec_to_jiffies(5)], I googled for a long time, but it seems that there is no explanation. Anyone knows why and can give any explanation? Thanks very much! Best Regards! ShiJinghui -- 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