On Sun, 4 Sep 2005, Karl Hiramoto wrote: > I've had the same problems with full speed devices on high speed hubs, > does anyone know if this is a hardware, or software problem?
That's a very different matter. It is a software problem; a limitation in the EHCI driver. There has been some recent work to improve the driver, but it hasn't gotten much exposure yet. For more information, look at http://www.linux-usb.org/usb2.html See especially the sections about Transaction Translators and Linux Status. > Andy Dalton wrote: > > >Alan, > > > >Thank you very much for your quick response. I was able to test your > >suggestion today and it worked like a charm. I do have another > >question, however. Is it possible to configure a hub to run at > >full-speed instead of high-speed in software? I can imagine a > >theoretical situation where I might like to have both full-speed and > >high-speed devices connected to the same system (on different hubs). There was another suggestion a couple of months ago for adding a way to force a high-speed device to run at full speed. So far nothing has been done, but it's a worthwhile idea. There's no way to configure a USB 2.0 hub to run at full speed. It's part of the USB 2.0 spec that hubs _must_ run at high speed when they are plugged into a high-speed capable port. It _is_ possible in principle to force a port on the computer into full speed, but as I mentioned, there's currently no API for doing this in Linux. Of course, if you want to have both full-speed and high-speed devices connected at the same time, on different hubs, all you really have to do is buy a USB 1.1 hub. Alan Stern ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
