On Tue, 23 Jan 2007, Pavel Machek wrote: > > > > Plug/unplug should be easy enough to simulate from usb driver, no? > > > > > > If that is true then I would be very interested in knowing how. > > > I, too, am confronted with USB device error conditions which I > > > don't know how to clear except by telling the user to unplug the > > > device. > > > > It depends on exactly what you want. Lots of things happen when a USB > > device is plugged in, and some of them can be simulated more easily than > > others. > > > > For instance, if the device is bus-powered then it goes from a power-off > > to a power-on state. This cannot be simulated. > > I thought it was possible to tell hub to power down single port -- at > least on some hubs?
Well, you can always _tell_ the hub to power down a single port, but lots of hubs won't actually _do_ it. For instance, the root hubs built into common USB host controllers won't. Some external hubs will acknowledge the command, disable the port, and claim to have powered it down but actually leave the power turned on. There are a few brands which really do implement the command properly. Furthermore, some hubs (probably not too many nowadays, but the spec allows for it) have ganged power-switching. This means you can shut down power to one port only by also shutting down power to all the other ports ganged along with it. Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
