[Linux-parport] IRQ storm from Express card parallel port

Andre Puschmann andre.puschmann at tu-ilmenau.de
Mon Jun 25 06:44:24 EDT 2012

Hi Martin,

On 06/25/2012 12:10 PM, Martin Mokrejs wrote:
> Hi Andre,
>   I played with a card from another vendor based on MosChip. It was stated
> in the manual one cannot use IRQ, only memory-mapped IO. When I did use ECP+DMA
> my Linux locked up soon. I could print fine but to scan a page I need a lot of luck.
> Well, I need a patch which you can find on this list to disable to "fix" which
> disabled ECP on many systems, inadverently, and was still necessary for 3.2.5 kernel.
> I am attaching them for your convenience.
>   I was dreaming about http://www.usbgear.com/USBG-EX-LPT.html which is based
> on Oxford chipset, hopefully working in IRQ mode as well.

Well, I am not 100% certain but the card came with a driver CD and it
contains a inf file for Windows which is copyright by Oxford Technology.
So that might mean that my adapter has the Oxford chip. Is there any way
to check without breaking the housing?

>   It probably not much helpful answer but that's all I could contribute, from my user
> experience. Threads on HPLIP forums merely document that scanning does not work
> over these adapters, mention some "soft" ECP mode used by HP printers/scanners
> if I remember right. Lookup the archives of this list, I think2 I posted some
> URLs while it was fresh in my memory. In the end I gave up.

Mmh, do you think the ECP patches help fixing this IRQ issues?


> Andre Puschmann wrote:
>> Hi,
>> I've been looking at using a Express card to parallel port adapter to
>> connect an external device to a PC without on-board parallel port. I got
>> an adapter from Delock [1] which seems to work fine at first glance.
>> Unfortunately, the IRQ handling seems to have problems. Whenever I
>> trigger the first IRQ (I've just shortened pin 10 and ground), I receive
>> an infinite number of IRQ from the parallel port which only stop after
>> unloading the kernel modules. The testing code [2] works fine on another
>> machine with on-board parallel port. I am using the standard Ubuntu
>> 12.04 LTS kernel (3.2.0-25). I am wondering whether anybody else has
>> observed such a strange behaviour before? It might be also related to
>> Guan Xin's post "[BUG] IRQ storm from linux/drivers/char/ppdev.c".
>> Thanks
>> Andre
>> [1] http://www.delock.de/produkte/F_263_Parallel_66220/merkmale.html
>> [2] https://github.com/andrepuschmann/lptirq
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Andre Puschmann
Ilmenau University of Technology, Integrated Communication Systems Group
Cognitive Radio Network Group
Phone: +49 3677 69-4132, Fax: +49 3677 69-1614
Email: andre.puschmann at tu-ilmenau.de, Web: http://www.tu-ilmenau.de/crng
Office: Zuse Building, room 1071

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