On Tue, 6 Sep 2005, Franck wrote: > Alan, > > 2005/9/5, Alan Stern <[EMAIL PROTECTED]>: > > > > On the third hand, who would ever make an embedded hub with only one, > > > > fixed downstream port? Why not leave out the hub and attach the > > > > upstream > > > > port directly to the downstream device? > > > > > > > > > > surely because the downstream device is a high speed device ? > > > > That's not a good reason. The internal hub is also a high-speed device. > > What advantage is there in putting the hub between the device and the > > upstream port? > > > > USB 2.0 spec, chapter 5-2-3. Doesn't it mean that a hub isolates the > full/low speed environment from the high speed one ?
You've got it backward. If the upstream environment is high speed and the downstream device is full/low speed, then the hub isolates one from the other. But if upstream is full speed and the downstream device is high speed, the hub serves no purpose. 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 _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
