Re: symbol DS6708 - problems under new kernels

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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
> 
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