Re: IORESOURCE_PCI_FIXED usage in pcibios_fixup_device_resources()

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Thursday, June 03, 2010 06:42:53 pm Paul Mundt wrote:
> On Thu, Jun 03, 2010 at 04:38:32PM -0600, Bjorn Helgaas wrote:
> > The SH implementation of pcibios_fixup_device_resources() does the
> > equivalent of pcibios_bus_to_resource() for all the resources of a
> > device, except that it skips resources with the IORESOURCE_PCI_FIXED
> > flag set.
> > 
> > This looks like a bug to me.  IORESOURCE_PCI_FIXED means the resource
> > cannot be moved, not that we should skip pcibios_bus_to_resource().
> > 
> > Does anybody know why pcibios_fixup_device_resources() does this check?
> > 
> > The only other IORESOURCE_PCI_FIXED reference I see in arch/sh is in
> > gapspci_fixup_resources(), so maybe it has something to do with that?
> > 
> gapspci is a very special case, in that it's not really PCI but a bit of
> mangling logic in a custom ASIC that interfaces an 8139 ethernet device
> directly on to an ISA-style bus. If you take a look at
> arch/sh/drivers/pci/fixups-dreamcast.c you can see where the flag is set
> and the rationale behind it.

Yes, using IORESOURCE_PCI_FIXED in gapspci_fixup_resources() sounds
reasonable; it's just that it doesn't make sense to test for it in
pcibios_fixup_device_resources() or pcibios_bus_to_resource().

> Looking at the code again though it seems like pcibios_bus_to_resource()
> will not cause any problems, especially given that the io and mem offsets
> are both cleared to 0 for that controller. I'll kill off the test from
> pcibios_fixup_device_resources(), I assume this was a remnant from the
> old pci-auto code which we moved off of some time ago.

Thanks.  I'll watch for your checkin.  I'm working on some patches
to move the generic parts of pcibios_fixup_bus() out of the arches
and into drivers/pci, and that depends on this change.

Bjorn