[PARPORT] RE: [patch] ieee1284 nibble mode

Tim Waugh (twaugh@matra.co.uk)
Thu, 21 Jan 1999 10:31:02 -0000

> > fudge delay needs to be longer to accommodate your printer as well.
> The error signal seems to be logical and _not_ timing related.

Presumably you tried altering the delay before deducing that?

> Do you want to force me to not use parport_probe? ;).

Of course not, Andrea. Do you want to force people not to use status

> I am not asking to
> include it in your tree, I only told you what an Epson Stylus Color 740
> need to work _fine_.

1) Reading /dev/lp0 should not give device ID information, at least not
without an ioctl to say that's what you want.
2) Waiting for a timeout to find out that the device has finished should not
be needed.

> Now that for the first time in my life it works I get:
> > root@laser:/home/andrea# cat /dev/lp0
> It change when something change in the printer.

The device ID changes? Interesting indeed. Which fields change - the
manufacturer, command set, model number or device class? Personally I think
that _any_ of those fields changing would be a neat trick.

> I have no ida of what is device ID (a real fix is welcome, I guess I had
> to ask for some parport_negotiate() in lp_read() in the same way we just
> do in parport_probe()).

Yes - that's how I test that readback works. My printer doesn't give any
status information, but the mechanism, as far as lp is concerned, is the

> I know how to make the code working though ;).

When you say that it works, is this with a timeout determining when to stop?

> > This is not acceptable.
> It has to become acceptable or I should do more reverse engeneering to
> understand what the ERROR line means here and how could I make it working
> here too

I'll take the second option, if you don't mind.

> But I don't have the real specs, so I couldn't know if the data-ready
> indication was an hack as the Canon one. See things from my
> point of view
> ;).

Did it look like a hack?

If we have to put hacks in to accommodate your printer as well as mine, I'd
rather they both went into the same line of code, i.e. the udelay.


twaugh@matra.co.uk     MATRA Systems (UK) Ltd., Home Farm, Leigh Road,
                       Eastleigh, SO50 9EU  Registered in Cardiff 2642797

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