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From: "Dunlap, Randy" <randy.dunlap@intel.com>
To: "'David Ford'" <david@linux.com>, Greg KH <greg@wirex.com>
Cc: linux-kernel@vger.kernel.org
Subject: RE: [bug] usb-uhci locks up on boot half the time
Date: Thu, 9 Nov 2000 09:06:31 -0800 
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> From: David Ford [mailto:david@linux.com]
> 
[snip]
> > Is the external hub a externally powered hub, or self 
> powered hub (does
> > it get it's power from a plug in the wall, or from the USB 
> bus)?  Self
> > powered hubs are notoriously flaky and have been known to 
> > evil things to the USB bus.
> 
> Either.  Currently bus (self) powered.  This hub has worked 
> fine on my other
> computers without any adverse affect.

Bus-powered != self-powered.

Self-powered means that it has its own power cord.

Bus-powered means that it gets its power from the USB cable.

Unlike Greg, I would have said that bus-powered hubs
can be a problem -- especially when you plug too many
devices into them that need lots of power.  What we saw
at the USB PlugFest was hubs just shutting down when
we did this.  :(

~Randy

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