On Fri, 9 Jul 2010, Amit Nagal wrote: > > This is a good example. The kernel prints a warning message in the log > > when it sees an unpowered hub plugged into another unpowered hub. The > > fact that the warning isn't present in your log means that the hubs lie > > to the kernel: They don't tell it they are unpowered. Another way to > > see this is that the log doesn't include any messages about "hub > > controller current requirement"; these messages are skipped when the > > hub claims to be self-powered. > > > > You should be able to see this in the "lsusb -v" output for those hubs. > > > > > Ya with lsusb -v , hubs do claim to be sef powered . > lsusb -v log is attached . > > 1) But by lying to the kernel , what advantage do bus - powered hubs get ? I don't know. Probably no advantage. > can we conclude that such hubs design is not proper ? That's my conclusion. 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
