Re: USB IEEE1284 gadgets and ppdev

[Steve Underwood <steveu@coppice.org>]

Tim Waugh wrote:

>On Wed, Sep 25, 2002 at 08:01:29AM -0700, Greg KH wrote:
>
>  
>
>>I understand that the uss720 driver should register with parport, as
>>it is a USB to parallel port adapter, but the usblp driver should
>>not, as it is just a pass-through to a printer.  Do you see any
>>advantage to having usblp registering with parport?
>>    
>>
>
>Well, it would mean that ppdev could use it.  I understand that only a
>few functions of a normal parallel port could be implemented (read,
>write, get status).
>
>Alternatively I suppose I could get libieee1284 to grok /dev/usb/lp*.
>Steve---would that solve the problem that you're running into?
>
>Tim.
>*/
>  
>
Well, the application is this. A lot of industrial control, embedded 
processor development interfaces, and other stuff use a parallel port to 
connect to a PC. The parallel port has gone from some notebooks, and is 
soon to go from desktops too. I want to access some of those devices 
through a USB to IEEE1284 cable. If the programming interface is ppdev, 
that is great - no changes needed for code that already works with a 
real parallel port. If it requires a somewhat different API, that's no 
big deal. Being able to bit twiddle to the extent that ppdev allows is 
pretty important, though. I guess there may be some latency issues 
slowing the bit twiddling across a USB interface, but nothing's perfect.

Regards,
Steve