Re: USB bus power budget and hubs

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Am Samstag, 7. November 2009 18:06:05 schrieb Bruno Prémont:
> > When a hub is bus-powered, the USB specification does not allow it to
> > provide more than 100 mA to each port.  Since the Sandisk pen wants
> > more than 100 mA, the kernel rejects its configuration.  You can
> > override this decision if you want by writing the appropriate config
> > value to the pen's /sys/bus/usb/devices/.../bConfigurationValue file.
>
> That's a not so nice limitation of the spec... It would have been more
> useful if the "available" power could be forwarded to a single port of
> the HUB even if in that case 0ma remain for the other 3 ports.

Suppose we did this and somebody plugs in another device.
Do we refuse to service this device?

	Regards
		Oliver

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