On Mon, Feb 14, 2011 at 09:29:09AM -0500, David Pyke wrote: > I have a Vantec NexStar USB3 dock using the JMicron chipset on a NEC chipset > motherboard hub. The motherboard is a Asus P6X58D-E > > I am running 2.6.38-rc4 under Kubuntu > > The dock is recognized but doesn't seem to work (writes not committed,etc.) > unless I set the default on CONFIG_USB_GADGET_VBUS_DRAW to 500 (well, that's The gadget Kconfig has nothing to do with the host-side drivers to support your dock. > the only other setting I tried). I'm assuming that the dock is mis-reproting > it's needs but was wondering why the default is set to 2 in kconfig. The default is 2 because it's the bare minimum a USB device will draw (well, there are the ones which draw nothing). It's just a sensible default, manufacturers should fix up the device descriptors correctly instead of using that Kconfig entry :-) > I've asked the ubuntu kernel team and they referred me to you. > > Is there problem or potential problem if the default setting is changed to > 500? Yes, gadget drivers are also connected to OTG or Embedded hosts. Those, in most cases, can't source more than 1 or 2 unit loads (100 or 200mA), so if you make it 500mA, those won't get enumerated. Also, if you're behind a bus powered Hub, you can never get 500mA as the HUB already consumes at least 1 unit load for itself, again your device won't get enumerated. -- balbi -- 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
