Subject: Re: new printer port support?
To: David Young <>
From: Jaromir Dolecek <>
List: tech-kern
Date: 05/04/2004 09:56:02
David Young wrote:
> Say, there used to be some -current activity concerned with "advanced"
> parallel printing with DMA and such.  Is it very stable?  Is it faster
> than the old?  Does the GENERIC kernel use it?

It's definitely way faster, it supports ECP using the chip FIFO
or DMA.

However, it's not reliable yet. e.g. while it worked fine even
in ECP mode with one Canon printer, it doesn't work at all
with my HP printer even in stadard mode. More needs to be
done with the code doing polled i/o, it completely blocks
kernel (a.k.a delay(9)) for long periods of time ('long' as
in tens of seconds).

I'm thinking about complete rewrite of the chip I/O related
routines, perhaps moving it back to the form used in FreeBSD
and merging FreeBSD changes done meanwhile.
Shared interrupt handling has to be improved, too, in order
to make the puc(4) attachment reliable with >1 printer ports.

It's not 2.0 material. Perhaps it would make it into next
patch release. It's not enabled in GENERIC at the moment.

Jaromir Dolecek <>  
-=- We should be mindful of the potential goal, but as the Buddhist -=-
-=- masters say, ``You may notice during meditation that you        -=-
-=- sometimes levitate or glow.   Do not let this distract you.''   -=-