Bug#296687: Problem Fixed
On Mon, Feb 28, 2005 at 11:40:22PM -0800, David Lawyer wrote:
> On Tue, Mar 01, 2005 at 11:55:42AM +0900, Horms wrote:
> > On Fri, Feb 25, 2005 at 12:07:20AM -0800, David Lawyer wrote:
> > > I fixed the problem by setting the parallel port in the BIOS from ECP to
> > > SPP. Then the driver does software handshaking and my old printer works
> > > OK. So this is a problem with documentation. I just emailed the
> > > authors of the kernel docs on the parallel port and told them about this
> > > fix. So you could close this bug if you want to, although it would be
> > > nice if somehow the software configured it all.
> >
> > Hi David,
> >
> > are you suggesting that there should be a kernel option
> > to restrict the modes that the parallel port driver will
> > operate in - so that if you have older hardware it will only
> > use modes supported by the other end. Or are you suggesting
> > that the driver should autodetect this somehow. My knowledge
> > of the relevant specs are weak (non-existant), but the latter
> > sounds like it might not be possible.
>
> I think the latter may be possible if one has a modern (not over 20
> years old) parrallel port on their PC (like I do). There's a spec for
> negotiation between the two ports over the parallel cable. In my case,
> there would be no response from my printer and it would then be assumed
> by my PC that the printer port doesn't meet IEEE 1284 specs and thus use
> the old Centronics protocol known as SPP. But I don't know how the port
> tells that to Linux. The old protocol requires driver handshaking for
> every byte sent.
>
> I think that the BIOS allows setting SPP for cases where the software
> doesn't know about ECP. Since Linux knows about ECP and since ECP can
> fallback to SPP mode, it should have worked in ECP mode. So I now think
> it's a bug and needs to be fixed even though I found a work around to
> get my printer printing.
Sure, that makes sense to me.
> > In any case, have you considered reporting this to LKML and
> > the maintainers?
> How do I do this?
I would email the linux-kernel@vger.kernel.org and CC the listed in the
MAINTAINERS file. Actually, I see there is a list for parallel port
support, so you might be better off to mail that + CC the maintainers.
In any case, here is the info.
PARALLEL PORT SUPPORT
P: Phil Blundell
M: Philip.Blundell@pobox.com
P: Tim Waugh
M: tim@cyberelk.net
P: David Campbell
M: campbell@torque.net
P: Andrea Arcangeli
M: andrea@e-mind.com
L: linux-parport@lists.infradead.org
W: http://people.redhat.com/twaugh/parport/
S: Maintained
--
Horms
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