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    SubjectRe: Dual slot PCI riser messes up ivtv
    Hello!

    [problem with PCI riser card, hardware discussion]

    > First the riser card is a dual slot one , with a chip on it so I assumed
    > it is active. It has jumpers to set the device number of the upper slot
    > and the devices in the two slots have to share the IRQ. This is it
    > here :
    > www.tranquilpc.co.uk/support/Files/TPC014/Tranquil%20Riser.pdf

    No, that's not an active one as Krzysztof wrote already.
    The GAL only does some simple things.

    > Third : The bug lies in the situation where the PVR-150 card is in the
    > upper slot and the DVB card is in the lower slot, in which case the DVB
    > card does not work. That was the dmesg output I posted earlier.

    I have the 32bit version of these cards:
    http://paui.de/pub/archive/image/PCI_Riser_3x32bit_passive.jpg
    http://paui.de/pub/archive/image/PCI_Riser_3x64bit_passive.jpg

    As you can see, the cards are a 1:1 extension to the center slot.
    The lower as well as the upper slot gets the additional signals from
    the two small PCBs which are the four INTA...INTD and the REQest and
    GraNT lines. The IDSELect's are soldered via 220R resistors to some
    address lines.

    > Fourth : here's cat /proc/interrupts in the current working situation
    > with the PVR-150 card in the lower slot and the DVB card in the upper
    > slot.
    > 0: 64 IO-APIC-edge timer
    > 1: 1130 IO-APIC-edge i8042
    > 7: 0 IO-APIC-edge parport0
    > 8: 3 IO-APIC-edge rtc
    > 9: 0 IO-APIC-fasteoi acpi
    > 12: 4 IO-APIC-edge i8042
    > 14: 18035 IO-APIC-edge ide0
    > 17: 0 IO-APIC-fasteoi ohci_hcd:usb1
    > 18: 26 IO-APIC-fasteoi ohci_hcd:usb2
    > 19: 0 IO-APIC-fasteoi ohci_hcd:usb3
    > 20: 2 IO-APIC-fasteoi ehci_hcd:usb4
    > 21: 12329 IO-APIC-fasteoi eth1
    > 22: 16399 IO-APIC-fasteoi SiS SI7012
    > 23: 15020 IO-APIC-fasteoi saa7134[0], saa7134[0], ivtv0
    > NMI: 0
    > LOC: 757294
    > ERR: 0
    > MIS: 0
    >
    > As you can see the two cards are sharing the IRQ properly.

    IRQ sharing is possible. But on the PCI Bus, the usually four
    IRQ lines are wired in a "Round Robin" scheme to avoid IRQ sharing.

    Additionally, each slot gets a unique ID by wiring the IDSELect
    of the slot connector to an AD bus line on the motherboard as
    mentioned above.

    So, each slot with a ID get it's fixed IRQ routed (along with the
    REQn/GNTn lines). If the IDs and the IRQ lines don't fit together,
    you might run into problems like you mentioned.
    I think it's possible to tell the kernel the right ID-IRQ routing
    associations manually. But I think it's not easy to get the BIOS fixed.
    So, I suggest to figure out how the BIOS (the kernel get that
    info from the BIOS, AFAIK (is that correct?)) wants to see its IRQ
    on the IDs and rewire the riser card that they all fit together.

    Well... that's what I did some time ago. For me it is more easy
    to fit the hardware once to the default kernel settings instead of
    patching every kernel on my embedded platform.

    You can find some more details here:
    http://www.formfactors.org/developer%5Cspecs%5CATX_Spec_V1_0.pdf
    And there is the official PCI Spec at http://www.pcisig.com
    however you have to be a member of the PCI SIG.

    Good luck,
    --
    Clemens Koller
    _______________________________
    R&D Imaging Devices
    Anagramm GmbH
    Rupert-Mayer-Str. 45/1
    81379 Muenchen
    Germany

    http://www.anagramm-technology.com
    Phone: +49-89-741518-50
    Fax: +49-89-741518-19
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