Am Montag, 28. Dezember 2009 21:43:06 schrieb Sarah Sharp: > Let me see if I understand what you're proposing. We want to suspend > the entire system, which may or may not cause a loss of power to the > host controller. If there's a loss of power, we need to reset the host > controller and re-enumerate the devices. Yes. > Currently, we selectively suspend each device in the tree, starting from > the bottom and working our way to the root hub. Instead of doing that, > you want to suspend the entire bus at the roothub. Yes. According to section 7.1.7.6.1 of the USB 2.0 spec. > I think you might run into a snag with USB 3.0 hubs. Here's the quote > from section 10.8 of the USB 3.0 bus spec: > > "Global suspend/resume refers to the entire bus being suspended or resumed > without affecting any hub’s downstream facing port states; selective > suspend/resume refers to a downstream facing port of a hub being suspended or > resumed without affecting the hub state. SuperSpeed hubs only support > selective suspend and resume. They do not support global suspend and resume." Hm. Do we do PM operations for USB 3.0 devices at all right now? It seems to me that we'll have to redisign in a major way anyway for the Ux states. Regards Oliver -- 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
