Re: [PARPORT] Re: for people with printing problems with 2.1.104

David Campbell (
Thu, 28 May 1998 06:44:38 +0000

> Date: Wed, 27 May 1998 16:43:43 +0200 (CEST)
> From: Andrea Arcangeli <>
> To:, Tim Waugh <>
> Subject: [PARPORT] Re: for people with printing problems with 2.1.104

> On Wed, 27 May 1998, Andrea Arcangeli wrote:
> >I will sent to Andreas some debugging patch soon to understand at least if
> >the bug is in the parallel-port or in the parport code.
> Looking at the parport_pc code seems that we are initializing the ECR even
> if the ECR is not been detected.
> This patch should fix that.

I suggest taking a second look at that code. The same value is written to

If you remember that old style XT ports alias IO locations every 0x400,
this means that writing to ECR (base+0x401) is the same as writing to CTR
(base + 0x001). On newer chipsets if the ECR is not present then the write
disappears into the bit bucket.

All I am saying is just be very careful when writing to the ECP associated
registers as it may clobber older style hardware. If the suggested patch
does actually work (I would be supprised if it did) then the entire ECP
detection code needs to be reworked.

David Campbell

"All parallel ports are equal - Some are more equal than others"

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