Messages in this thread | | | Date | Tue, 12 Jun 2007 00:42:28 +0200 | From | Robert de Rooy <> | Subject | Re: [linux-usb-devel] ThinkPad T41 - Strange USB 2.0 behaviour |
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Alan Stern wrote: > Okay. It's clear that you've got a hardware problem of some sort. > Hard to say what it is, but evidently the EHCI controller thinks that > the device is repeatedly being unplugged and replugged. > > Anyway, this isn't a problem of recognizing that a single device is > having problems. In fact the computer has no way of knowing that a > single device is involved; all it knows is that _something_ gets > plugged into the port and then removed. There's no way to tell if it's > the same _something_ from one iteration to the next. > > You can manually force the port to run at full speed instead of high > speed as follows: > > echo '4' >/sys/class/usb_host/usb_host4/companion > > The "companion" attribute file contains a list of ports which are > permanently set to be handled by the EHCI's companion controller. To > return to high-speed operation, use '-4' instead of '4' above. This > might or might not solve your problem -- the hardware bug might cause > the port to return automatically to high-speed regardless. > > Let me know what happens. > > Alan Stern
Yes that works. I tried to plug and unplug the device repeatedly and each time it came up in full-speed mode.
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