Am Dienstag, 26. Juli 2011, 10:57:29 schrieben Sie: > Hi, > > On Tue, Jul 26, 2011 at 4:42 PM, Oliver Neukum <oneukum@xxxxxxx> wrote: > > Am Dienstag, 26. Juli 2011, 10:17:59 schrieb Ming Lei: > >> > This precise instruction is a fairly clear indication that the > >> > rhdev->bus_mA value is a per-port limit and not a global hub limit. > >> > Otherwise, there wouldn't have been this maximum value of 500mA. > >> > >> I understand 500mA is shared by all bus-powered devices attached to > >> the port of root hub, so rhdev->bus_mA should be used as global value. > >> And for each individual port of root hub, the max power is 500mA. > > > > Some very small battery powered devices (IIRC it was reported for a > > device called Spitz by Pavel Machek) cannot supply the full 500mA. > > Hence we have code to deal with this special situation. > > Currently hcd->power_budget is used for such purpose, for example, the > max power provided by otg controller is 100mA. > > But what Thomas is wanting is that the max power provided by > individual port in root hub can be customized, which is not supported > by current kernel, but looks like not difficult to do it. Indeed. This is being complicated by the power consumption being affected by configuration. You have to recalculate when a configuration is changed. 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
