Re: [PATCH] 2.6 SGI Altix I/O code reorganization

From: Jesse Barnes (jbarnes_at_engr.sgi.com)
Date: 10/06/04

  • Next message: Hanna Linder: "Re: 2.6.9-rc3-mm2"
    To: Grant Grundler <iod00d@hp.com>
    Date:	Wed, 6 Oct 2004 13:27:28 -0700
    
    

    On Wednesday, October 6, 2004 12:54 pm, Grant Grundler wrote:
    > Colin,
    > thanks for ACKing the feedback.
    > I think there is still some confusion...
    >
    > On Wed, Oct 06, 2004 at 02:09:54PM -0500, Colin Ngam wrote:
    > ...
    >
    > > > Mathew explained replacing the raw_pci_ops pointer is the Right Thing
    > > > and I suspect it's easier to properly implement.
    > >
    > > I believe we did just that. We did not touch pci_root_ops.
    >
    > Correct. The patch ignores/overides pci_root_ops with sn_pci_root_ops
    > (which is what I originally suggested).
    >
    > Mathew's point was only raw_pci_ops needs to point at a different
    > set of struct pci_raw_ops (see include/linux/pci.h).

    Though now what's there seems awfully redundant, wouldn't you say? Just
    allowing direct access to pci_root_ops is a much simpler approach and gets
    rid of a bunch of extra, unneeded code (i.e. closer to Pat's original
    version).

    > > Yes, would anybody allow us to make a platform specific callout
    > > from within generic pcibios_fixup_bus()???
    >
    > If it can be avoided, preferably not. But that's up to Jesse/Tony I think.

    If it was made a machine vector that's a no-op on everything but sn2, I think
    it would be fine. Doing it for the general sn_pci_init routine would let us
    get rid of the check for ia64_platform_is("sn2") in one of the routines, I
    think (which is nice if only for the consistency).

    > Can you quote the bit of the patch which implements "if the bus does not
    > exist" check?
    > I can't find it.

    In the current code it's:

     for (i = 0; i < PCI_BUSES_TO_SCAN; i++)
      if (pci_bus_to_vertex(i))
       pci_scan_bus(i, &sn_pci_ops, controller);

    which causes the next loop to only fixup existing busses. But I don't see it
    in the new code.

    > > One favour. Would you agree to letting this patch be included by Tony
    > > and we will come up with another patch to fix the 2 obvious items listed
    > > above? It will be great to avoid spinning this big patch.

    The patch is ok with me, I think it's a big improvement over what's there in
    terms of readability.

    I just checked out sn_set_affinity_irq() and it's a bit hard to see what's
    going on. Why does a new interrupt have to be allocated? Also, it looks
    like the kfree() is one line too high, if sn_intr_alloc fails, we'll leak
    new_sn_irq_info.

    Jesse
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