Messages in this thread | | | Date | Thu, 1 Jun 2006 11:23:44 -0400 | Subject | Re: USB devices fail unnecessarily on unpowered hubs | From | Lennart Sorensen <> |
| |
On Thu, Jun 01, 2006 at 11:09:46AM -0400, linux-os (Dick Johnson) wrote: > Many, most, perhaps all such devices don't take more power when they > are "enabled". Everything is already running and sucking up maximum > current when you plug it in! If the motherboard didn't smoke when > the device was plugged in, you might just as well let the user use > it! Perhaps a ** WARNING ** message somewhere, but by golly, they > got it running or else you wouldn't be able to read its parameters.
I imagine something like a harddisk might use more power while reading/writing than when it is just spinning. It might even start powered down until sent some command that causes it to spin up.
A scanner certainly uses more power with the scanner light on than with it off, and it starts out off until it is in use on most scanners. Of course I have never seen a usb powered scanner, so it doesn't seem to matter.
Len Sorensen - 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/
| |