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Hi! > Starting with 2.6.16, some USB devices fail unnecessarily on unpowered > hubs. Alan Stern explains, > > "The idea is that the kernel now keeps track of USB power budgets. When a > bus-powered device requires more current than its upstream hub is capable > of providing, the kernel will not configure it. > > Computers' USB ports are capable of providing a full 500 mA, so devices > plugged directly into the computer will work okay. However unpowered hubs > can provide only 100 mA to each port. Some devices require (or claim they > require) more current than that. As a result, they don't get configured > when plugged into an unpowered hub." Actually I have exactly opposite problem: my computer (spitz) can't supply full 500mA on its root hub, and linux tries to power up 'hungry' devices, anyway, leading to very weird behaviour. -- Thanks for all the (sleeping) penguins. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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