need help with my first device driver

[greg@kroah.com (Greg KH)]

On Tue, May 03, 2011 at 10:35:02PM +0530, Prashant Shah wrote:
> On Fri, Apr 29, 2011 at 8:51 PM, Greg KH <greg@kroah.com> wrote:
> > On Fri, Apr 29, 2011 at 03:10:53PM +0530, Prashant Shah wrote:
> >> Hi,
> >>
> >> I am trying to write a comedi (drivers/staging/comedi) based driver
> >> for the National Instruments USB 6008 USB based data acquisition card.
> >>
> 
> I want to ask a quick question on USB.
> 
> When I do a lsusb on the device it shows it has 4 end points (two bulk
> in and two bulk out). How do I send commands to the device since there
> are no control endpoints ?

It all depends on your device, what is the protocol for talking to your
device?  Some accept commands on bulk endpoints, others on the control
one.

And there is always endpoint 0, the default control endpoint, should you
use that?

> What I am doing currently is creating a
> bulk receive pipe and trying to read data in the completion handler
> but I dont get any data.

Are you sure data is being sent?  Did you ask the device to send it to
you with the correct command?  Your data sheet on the device should give
you the correct information on how to get data from your device, right?

hope this helps,

greg k-h