Multiple cards using same IRQ – getting IRQ errors and hissing

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I am running Asterisk, dahdi 2.4.0 and libpri on an
HP ML110 G6 using Ubuntu Linux 10.04 LTS.

I have two Digium TE121 single T1 port cards and a Digium AEX800
8-port FXS card. All PCI Express cards.

Co-workers are hearing hissing sounds on some calls, and I am getting
IRQ errors when running “dahdi show status”.

I see that sharing IRQs for Digium cards isn’t recommended, so I’m
trying to set it so each card gets its own. From the few web sites
I’ve read so far, including Digium’s FAQ site, I’ve added ACPI and
verified that the BIOS does not give me the ability to manually set
the IRQ. I’ve even taken one of the TE121’s out of the server (it
isn’t being used anyways). Everything I’ve done so far has not fixed
it. All the cards (as well as USB1) all use IRQ 16.

The other option given was to use setpci, but I am unfamiliar with
that command. I did what I could to try and find the setting (based
on what the man page on Ubuntu’s web site) where I could see the value
16, but not getting anywhere.

I know that this is more of an Asterisk forum than Digium. If I need
to put in a case at Digium I will, but wanted to see if there were any
suggestions here before I pursued that.

Any help would be appreciated.

Dean Hoover

One thought on - Multiple cards using same IRQ – getting IRQ errors and hissing

  • A month ago I had similar problems with a HP DL360g6 and a HP DL380g7
    running Debian 5 “Lenny”.
    In the HP DL360g6 I had one TE121. I noticed IRQ misses and the problem
    was easily reproduced
    by running dahdi_maint to enable loopback and patlooptest while
    compiling asterisk to create some i/o.

    When I installed Debian 6 “Squeeze” instead the problem went away.
    Tested with both servers above.
    On this page I found some information about APIC (Advanced Programmable
    Interupt Controller)
    (quite old but informative)

    I haven’t got the time to verify the root cause of the problem yet (I’ve
    planned to do this at the end of this month)
    but my theory is that it has something to do with the kernels APIC
    handling that was fixed between Debian 5 and 6.

    Maybe you experience something similar?