On Sun, 24 Sep 2006, Pavel Machek wrote:
I made some quick experiments, and usb still eats 4W of battery
power. (With whole machine eating 9W, that's kind of a big deal)...
This particular machine has usb bluetooth, but it can be disabled by
firmware, and appears unplugged. (I did that). It also has fingerprint
scanner, that can't be disabled, but that does not have driver (only
driven by useland, and was unused in this experiment).
(I have not followed the thread, so bear with me if I say anything
I have encountered at least 3 hubs (2 usb2 & 1 usb1) that will consume a
lot of power (about 2-2.5W if the laptop power consumption readings are to
be trusted) and heat up a lot (to the point of being too hot to touch for
more than a few seconds) even when no devices are connected, at least on
Linux. I have not tested them on a Windows machine to see if this is the
case there. The USB2 ones used Cypress chips. I do not know what your h/w
config is, but perhaps this is a similar case ?
PS: Note that the 2-2.5W consumption is the maximum that the laptop USB
port can provide, and I have noticed that with the hub's external power
supply connected it heats up even more.
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