Need docs on USB driver development

[Bernd Walter]

On Tue, Feb 12, 2008 at 04:03:27AM +0300, Dmitry Marakasov wrote:
> * Dmitry Marakasov (amdmi3 at amdmi3.ru) wrote:
> 
> > work through neither uhid nor ugen drivers (though I'm gonna do
> > some more digging here). So I've decided to go level lower and write
> Upd: I was able to make it work through ugen. By the chance I've plugged
> the device into another slot, and it worked.
> 
> So the curious thing is that it works like that:
> addr 1: UHCI root hub, Intel
>  addr 3: AVerMedia USB Radio, AVerMedia Technologies
> 
> (can write commands to /dev/ugen0.2)
> 
> But not like that:
> addr 1: OHCI root hub, NEC
>  addr 2: AVerMedia USB Radio, AVerMedia Technologies
> 
> (writing to /dev/ugen0.2 fails with EIO)

Some devices are way to sensitive to noise and sometimes even timing.
What you see is very likely a transmission error because of hardware
problems and not of software.
I would say the device is just badly designed.
You may even change the situation by adding an hub between.

-- 
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