On Fri, 4 Mar 2011, jpo234 wrote: > Hello all, > I just learned that my initial description is not quite correct. The > issue is a "fuse" that switches off the power to a USB port when the > amperage reaches a threshold. This threshold is supposedly software > configurable. In our case the threshold is 150mA and the attached device > draws 147mA. Because this is so close to the threshold the device > randomly works or not. > To re frame my original question: Is this picture valid? Is there support > in Linux to adjust this threshold? If so, how? It all depends on what type of USB port hardware you're talking about. The hardware used in most desktop and laptop computers has a current limiter set for 500 mA, not 150 mA. There is no way to change its setting in software. The same is true for most powered hubs. For unpowered hubs, the limiter is set to 100 mA. Alan Stern -- 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
