Re: [PATCH] PPC: PCI: Fix pcibios_io_space_offset() so it works for 32-bit ptr/64-bit rsrcs

On Jun 6, 2012, at 5:15 PM, Scott Wood wrote:

On 06/05/2012 10:50 PM, Ben Collins wrote:

quoted

The commit introducing pcibios_io_space_offset() was ignoring 32-bit =

to

quoted

64-bit sign extention, which is the case on ppc32 with 64-bit =

resource

quoted

addresses. This only seems to have shown up while running under QEMU =

for

quoted

e500mc target. It may or may be suboptimal that QEMU has an IO base
address > 32-bits for the e500-pci implementation, but 1) it's still =

a

quoted

regression and 2) it's more correct to handle things this way.

=20
Where do you see addresses over 32 bits in QEMU's e500-pci, at least
with current mainline QEMU and the mpc8544ds model?
=20
I/O space should be at 0xe1000000.

The problem is this:

pci_bus 0000:00: root bus resource [io  0xffbed000-0xffbfcfff] (bus =
address [0x100000000-0x10000ffff])

Without the fix that I sent, it ends up looking like:

pci_bus 0000:00: root bus resource [io  0xffbed000-0xffbfcfff] (bus =
address [0x0000-0xffff])

And that's when some devices fail to be assigned valid bar 0's and the =
kernel complains because of it.

I'm also not sure what this has to do with the virtual address =

returned

by ioremap().
=20

quoted

Signed-off-by: Ben Collins <redacted>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/kernel/pci-common.c |    8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
=20

diff --git a/arch/powerpc/kernel/pci-common.c =

b/arch/powerpc/kernel/pci-common.c

quoted

index 8e78e93..be9ced7 100644

--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c

@@ -1477,9 +1477,15 @@ int pcibios_enable_device(struct pci_dev *dev, =

int mask)

quoted

	return pci_enable_resources(dev, mask);
}
=20
+/* Before assuming too much here, take care to realize that we need =

sign

quoted

+ * extension from 32-bit pointers to 64-bit resource addresses to =

work.

quoted

+ */
resource_size_t pcibios_io_space_offset(struct pci_controller *hose)
{
-	return (unsigned long) hose->io_base_virt - _IO_BASE;
+	long vbase =3D (long)hose->io_base_virt;
+	long io_base =3D _IO_BASE;
+
+	return (resource_size_t)(vbase - io_base);

=20
Why do we want sign extension here?
=20
If we do want it, there are a lot of other places in this file where =

the

same calculation is done.
=20
-Scott
=20

--
Ben Collins
Servergy, Inc.
(757) 243-7557

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