On Tuesday 26 April 2005 11:33 am, Alan Stern wrote: > On Mon, 25 Apr 2005, David Brownell wrote: > > > 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? > > It can't. Or with patch as478b, it can by calling usb_hcd_poll_rh_status > -- but that won't accomplish anything (other than invoking the hub_status > callback) until the root hub has been registered. So what? Does this > cause any kind of problem?
Lost events are to be avoided... > So this won't matter once usb_hcd_root_hub_lost_power is written, right? Shouldn't, if it's done right. But you were asking about why it's done that way _now_, and that's the answer. > > > 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. > > From the USB specification, table 11-13 (p.418): > > 6 bHubContrCurrent 1 Maximum current requirements of the Hub Controller > electronics in mA. I wasn't talking about the controller itself ... I was talking about its power budget. Different concepts. - Dave ------------------------------------------------------- SF.Net email is sponsored by: Tell us your software development plans! Take this survey and enter to win a one-year sub to SourceForge.net Plus IDC's 2005 look-ahead and a copy of this survey Click here to start! http://www.idcswdc.com/cgi-bin/survey?id=105hix _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
