USB IEEE1284 gadgets and ppdev

USB IEEE1284 gadgets and ppdev

[Steve Underwood]

Hi,

Can the USB driver for USB to IEEE1284 gadgets be used with the ppdev 
interface? I looked through the documentation and couldn't find a 
mention of this one way or the other. The structures used by parport and 
the USB stuff look similar, but I couldn't see how to get ppdev to play 
with the USB driver.

The documentation tells you how to do this using the special driver for 
those USB to IEEE1284 devices using the USS720 chip, but I have yet to 
see anything using that available for sale in these parts.

Regards,
Steve

Re: USB IEEE1284 gadgets and ppdev

[Tim Waugh]

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On Tue, Sep 24, 2002 at 11:22:02PM +0800, Steve Underwood wrote:

> Can the USB driver for USB to IEEE1284 gadgets be used with the ppdev 
> interface? I looked through the documentation and couldn't find a 
> mention of this one way or the other. The structures used by parport and 
> the USB stuff look similar, but I couldn't see how to get ppdev to play 
> with the USB driver.

Which driver are you using?  It ought to be hooked into the parport
stuff (parport_register_driver etc) like USS720, and then it'll work.

Tim.
*/

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Re: USB IEEE1284 gadgets and ppdev

[Steve Underwood]

Tim Waugh wrote:

>On Tue, Sep 24, 2002 at 11:22:02PM +0800, Steve Underwood wrote:
>
>  
>
>>Can the USB driver for USB to IEEE1284 gadgets be used with the ppdev 
>>interface? I looked through the documentation and couldn't find a 
>>mention of this one way or the other. The structures used by parport and 
>>the USB stuff look similar, but I couldn't see how to get ppdev to play 
>>with the USB driver.
>>    
>>
>
>Which driver are you using?  It ought to be hooked into the parport
>stuff (parport_register_driver etc) like USS720, and then it'll work.
>
>Tim.
>*/
>  
>
Thanks for responding.

As far as I can tell there are only two USB drivers for USB-to-IEEE1284 
devices - USS720 for the USS720 device, and usblp for everything else. 
Is usblp supposed to hook into ppdev? Is there some other device driver 
I missed?

Regards,
Steve

Re: USB IEEE1284 gadgets and ppdev

[Tim Waugh]

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On Wed, Sep 25, 2002 at 09:51:20PM +0800, Steve Underwood wrote:

> As far as I can tell there are only two USB drivers for USB-to-IEEE1284 
> devices - USS720 for the USS720 device, and usblp for everything else. 
> Is usblp supposed to hook into ppdev? Is there some other device driver 
> I missed?

Not into ppdev; into parport.  It ought to use
parport_register_port. (It doesn't, currently.)

Tim.
*/

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Re: USB IEEE1284 gadgets and ppdev

[Greg KH]

On Wed, Sep 25, 2002 at 03:27:57PM +0100, Tim Waugh wrote:
> On Wed, Sep 25, 2002 at 09:51:20PM +0800, Steve Underwood wrote:
> 
> > As far as I can tell there are only two USB drivers for USB-to-IEEE1284 
> > devices - USS720 for the USS720 device, and usblp for everything else. 
> > Is usblp supposed to hook into ppdev? Is there some other device driver 
> > I missed?
> 
> Not into ppdev; into parport.  It ought to use
> parport_register_port. (It doesn't, currently.)

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?

thanks,

greg k-h

Re: USB IEEE1284 gadgets and ppdev

[Tim Waugh]

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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.
*/

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Re: USB IEEE1284 gadgets and ppdev

[Steve Underwood]

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

Re: USB IEEE1284 gadgets and ppdev

[Tim Waugh]

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On Tue, Oct 01, 2002 at 11:35:53PM +0800, Steve Underwood wrote:

> Being able to bit twiddle to the extent that ppdev allows is pretty
> important, though.

Well, usblp wouldn't let you do any more than /dev/lp0 currently does,
really.  It sounds like you want support for more uss720-like
devices.

Tim.
*/

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