Re: PCI bookkeeping

From: Martin Mares (mj@suse.cz)
Date: Sat Oct 21 2000 - 17:37:42 EDT

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    Hello!

    > The problem I'm seeing is that at least one driver
    > has signed up to handle the wrong IRQ because,
    > when it queried that PCI config value, it went
    > back and got it from PCI config space rather
    > than from the in-kernel data structures where the
    > (correct) recalculated value had been stored. So,
    > I'm wondering if our Official Approach is to always
    > query the in-kernel data structures which have
    > been setup so nicely for us, or are we supposed
    > to obtain (some or all of) that sort of info from
    > PCI space? Or is this all just a bleeding mess?

    The only correct way to get the IRQ number for a given PCI card is to look
    to the pci_dev structure. This holds for both 2.2 and 2.4 kernels. (The main
    reason being that on some architectures the interrupt number doesn't fit
    in a single byte.)

    If you know of any drivers reading interrupt line information from the
    configuration space, please tell us and we'll fix them.

                                    Have a nice fortnight

    -- 
    Martin `MJ' Mares <mj@ucw.cz> <mj@suse.cz> http://atrey.karlin.mff.cuni.cz/~mj/
    "Immanuel doesn't pun, he Kant."
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