> Yes > > >> reported as self powered, per port power limit is 500 mA, so the > >> device may be configured and maybe work normal. > >> > > > > I see your hub report its max power is 100 mA, so if it can report as > > self powered, then the hub's behavior is correct, and will not be > > rejected by kernel. And you should get an error message when the > > device which declares its max power larger than 100mA plugs in hub's port, > right? > > The external hub could be enumerated regardless of it's reported to linux as > self-powered or bus-powered. > The difference is that when it's reported as self-powered / bus-powered, > driver will set the per port power limit to 500 mA / 100 mA. When a usb device > is attached to one port of the hub, driver will compare the MaxPower of the > configuration of the device with the hub port power limit, if the MaxPower is > greater than the port power limit, the configuration will be rejected. > > >> But will it cause a runtime error? Say I have a embeded usb host > >> which can supply 500 mA at most, when the hub reported as self > >> powered and attached with two devices both with max power equals to > >> 250 mA. Both device can be configured, but if they are both working > >> at the most power requirement at the same time, there should be some > power problem, right? > >> So, the current hub code is correct, the Lab will use the well-behavior hub, it should no problem for this test item, right?
Peter
