On Friday 22 April 2005 8:23 pm, Alan Stern wrote: > In theory an HCD shouldn't care one way or another about whether the root > hub has been registered. As Oliver likes to say, it would be a layering > violation. The HCD should concern itself only with the hardware.
Right, but if usbcore says "activate the root hub" then port change IRQs can come immediately. And then how can the HCD tell usbcore to collect that status, if hasn't registeed the root hub? > > > Yes. I just don't see any reason for setting the state to CONFIGURED, > > > since that's what it should be already. > > > > It would have been, before the reset. When you reset a device, it > > can't stay in the CONFIGURED state. (But maybe details changed since > > then...) > > Maybe they have; it depends on what you mean by "reset". A port reset > will change the state, whereas usb_reset_device often won't. However > neither of those resets applies to root hubs. I think the reset you're > referring to is something internal to ehci-hcd, which doesn't change the > root hub's state at all. Well, if it resets all the ports, then it's clearly affected the root hub's state. Think of it as another case where that "disconnect the usb whole tree" primitive would kick in, too ... > since the descriptor only allows for power consumption up to 255 ma, which > might not be high enough to express the requirements of some controllers. Erm, the units are 2mA and the max is 250 units, so that's 500 mA. Self powered hubs can do 500 mA per port. Bus powered ones can't; neither can all root hubs. - Dave ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
