On Mon, 2007-12-24 at 00:23 -0700, Grant Grundler wrote:
> On Tue, Dec 18, 2007 at 10:01:15AM +1100, Benjamin Herrenschmidt wrote:
> > This patch changes the PowerPC PCI code to disable IO and/or Memory
> > decoding on a PCI device when a resource of that type failed to be
> > allocated. This is done to avoid having unallocated dangling BARs enabled
> > that might try to decode on top of other devices.
> >
> > If a proper resource is assigned later on, then pci_enable_device{,_io,_mem}
> > will take care of re-enabling decoding.
> >
> > Signed-off-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
> ....
> > @@ -1062,8 +1065,12 @@ static void __init pcibios_allocate_reso
> > disabled = !(command & PCI_COMMAND_IO);
> > else
> > disabled = !(command & PCI_COMMAND_MEMORY);
> > - if (pass == disabled)
> > - alloc_resource(dev, idx);
> > + if (pass == disabled && alloc_resource(dev, idx)) {
> > + command &= ~(r->flags & (IORESOURCE_IO |
> > + IORESOURCE_MEM));
>
> While this may be ok for PPC, in general, wouldn't we want to only disable
> which ever type of resource that couldn't be allocated?
This is exactly what's supposed to be happening, but the code is buggy
and nobody noticed :-) (I'm mixing up IORESOURCE_* flags and
PCI_COMMAND_* flags). Thanks for reviewing !
> ie make two calls: alloc_resource_io() and alloc_resource_mem() and disable
> the respective flag if the alloc call fails?
No need for 2 calls, just disable whatever type the resource is, but
using the right bits instead of what my code incorrectly does.
> Thus a device which was enable and programmed by BIOS could remain functional
> despite one resource not being allocated.
Yes, that's what intended by the above code, if I didn't have mixed up
the flags.
Ben.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
