Passmark USB loopback test plugs

Felipe Balbi felipebalbi at
Tue Nov 20 20:39:35 UTC 2007

On Nov 20, 2007 4:33 PM, Matthias Urlichs <smurf at> wrote:
> Hi,
> Felipe Balbi:
> > Greg KH:
> > > My question is _why_ does it need to be a kernel driver, why can't this
> > > all be done in userspace instead?
> >
> > Using a sysfs interface (aka linux device driver), looks better to me,
> Umm, "looks better" isn't a reason we can have a discussion about.

quite extense, btw

> Why would you want to export any result from sysfs if a libusb program
> can collect the data directly? Given that "real" applications for "real"
> devices will want to move data from and to userspace eventually, a
> loopback test that doesn't even touch userspace seems to me to be kindof
> unrealistic and therefore of questionable utility.

this is also a matter of what you like better, kernel can handle all
test scenarios internally,
and in case of musb driver 'twas better letting kernel do it since i
had to play with
musb's registers in order to see the test running.

It wasn't just a matter of sending a control message and waiting for an answer.

> --
> Matthias Urlichs   |   {M:U} IT Design @   |  smurf at
> Disclaimer: The quote was selected randomly. Really. |
>  - -
> Nothing so needs reforming as other people's habits.

Best Regards,

Felipe Balbi
felipebalbi at

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