# Re: \[PATCH V7 1/3\] powerpc/pci: Make sure ISA IO base is not zero

- From: Benjamin Herrenschmidt \<benh@kernel.crashing.org\>
- Date: 2012-08-15 21:33:15 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2012/08/9470828
- Thread: https://ratatoskr.run/linuxppc-dev/2012/08/9470815/t.md

```text
On Wed, 2012-08-15 at 12:29 -0500, Scott Wood wrote:
> > ---
> >  arch/powerpc/kernel/pci-common.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> > index 0f75bd5..2a09aa5 100644
> > --- a/arch/powerpc/kernel/pci-common.c
> > +++ b/arch/powerpc/kernel/pci-common.c
> > @@ -734,7 +734,7 @@ void __devinit pci_process_bridge_OF_ranges(struct pci_controller *hose,
> >  			hose->io_base_virt = ioremap(cpu_addr, size);
> >  
> >  			/* Expect trouble if pci_addr is not 0 */
> > -			if (primary)
> > +			if (primary || !isa_io_base)
> >  				isa_io_base =
> >  					(unsigned long)hose->io_base_virt;
> >  #endif /* CONFIG_PPC32 */
> > 
> 
> Didn't I already point out that this has problems when the primary bus
> is not the first to be probed?  If your answer is that you fix that in a
> later patch, that breaks bisectability.

Is it though ? ie, we will override it with the real primary in the
above test, so it will only very temporarily be set to the "wrong" bus
no ? IE, the test will still trip on the actual "primary" if there's
one.

Cheers,
Ben.
```