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

[Jesse Barnes <jbarnes@engr.sgi.com>]

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