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

Andre Puschmann andre.puschmann at tu-ilmenau.de
Mon Jun 25 04:08:25 EDT 2012


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".


[1] http://www.delock.de/produkte/F_263_Parallel_66220/merkmale.html
[2] https://github.com/andrepuschmann/lptirq

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