When I moved from 2.6.27 to 2.6.28, one of my devices didn't work
until I devised the attached patch. The kernel disallowed PCI I/O
space resources behind the pseudo-bridge in the Freescale MPC8545
because that bridge's config-space registers incorrectly report that
it doesn't forward I/O space transactions.
Checking for a specific vendor ID is hacky, but it got my system going
again with only a few perturbed lines. Is there a more correct way to
achieve this?
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index f36936d..f9f0048 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -985,6 +985,7 @@ static int __devinit
pcibios_uninitialized_bridge_resource(struct pci_bus *bus,
struct pci_dev *dev = bus->self;
resource_size_t offset;
u16 command;
+ u16 vendor;
int i;
/* We don't do anything if PCI_PROBE_ONLY is set */
@@ -1030,7 +1031,16 @@ static int __devinit
pcibios_uninitialized_bridge_resource(struct pci_bus *bus,
* starting at low addresses -is- valid. What we do instead if
that
* we consider as unassigned anything that doesn't have IO
enabled
* in the PCI command register, and that's it.
+ * However, we don't do that if the bridge is internal to a
Freescale
+ * CPU, as such bridges break the rules by, for example, not
populating
+ * the PCI_COMMAND_IO bit.
*/
+ pci_read_config_word(dev, PCI_VENDOR_ID, &vendor);
+ if (vendor == PCI_VENDOR_ID_MOTOROLA ||
+ vendor == PCI_VENDOR_ID_FREESCALE) {
+ return 0;
+ }
+
pci_read_config_word(dev, PCI_COMMAND, &command);
if (command & PCI_COMMAND_IO)
return 0;
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