Hello Alan, thanks for your reply..
> There are devices like this. They only work under certain conditions. > I have a USB disk drive enclosure which works okay if you power it up > and then plug the USB cable into the computer, but not if you do these > things in the opposite order. I agree that this is probably a hardware issue.. but the problem is it was warking before and the customer has hundreds of those deployed, so there's a big pressure to have it fixed in software, as hardware solution (either some kind of power switch or even replacement) is not an option :( a bit desperate, but I'll have to try bisecting it.. I'll report if I find something BR nik > > > Our guess is it has something to do with power, as using the ammeter > > it seems that when the device is not working, it just takes very little > > current, so maybe it just doesn't "tell" the bus to increase voltage > > at start? > > > > A colleague has developped solution to fix on ehci-hcd managed ports > > using unbind/bind of the particular device, so we can "fix" it automatically > > on boot. However it doesn't work/help on other USB buses, ie uhci-hcd > > or xhci-hcd (this is on new models and was not been used on SUSE at all) > > > > Sometimes reloading usb module helps, but sometimes not. > > > > My question is, did somebody have/solve similar issue? Is there a way > > to decrease/increase power in generic way, so I can subsctitute device > > unplug/plug? Or maybe some even better any better way I could use to > > solve this issue? There are hundreds of those readers in production, > > so replacing them is a problem.. > > One possibility is to plug the reader into a hub with true port-power > switching. (Lots of hubs don't have power switching on their ports, > but some models do.) Then you will be able to run a program after boot > that will turn off power to the hub's ports and then turn it back on. > > Most desktop and laptop computers are not able to turn off power to > their USB ports. > > Alan Stern > > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- ------------------------------------- Ing. Nikola CIPRICH LinuxBox.cz, s.r.o. 28.rijna 168, 709 00 Ostrava tel.: +420 591 166 214 fax: +420 596 621 273 mobil: +420 777 093 799 www.linuxbox.cz mobil servis: +420 737 238 656 email servis: ser...@linuxbox.cz ------------------------------------- -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
