On Thu, 1 Sep 2005, Franck wrote: > Hi, > > Is it really needed to poll an embedded hub that has only one > downstream port on which a device is plugged forever ?
It depends. If the device can be suspended and is a wakeup source then the polling is needed, at least whenever the device is suspended. Otherwise the polling doesn't accomplish much. > If no, Is there > a way to detect it and to avoid useless work ? Sure. All the information in the hub descriptor is available, including the number of ports and whether they are fixed or removable. On the other hand, it's not really all that much useless work. 4 times per second or so there's a single, very short transaction (IN followed by NAK). Unless you've got some good reason for avoiding it, why bother? 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? 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
