| Submitter | Andrew Klossner |
|---|---|
| Date | Jan. 14, 2009, 7:48 p.m. |
| Message ID | <200901141948.n0EJmXH3002897@pogo.cesa.opbu.xerox.com> |
| Download | mbox | patch |
| Permalink | /patch/18527/ |
| State | Deferred |
| Delegated to: | Kumar Gala |
| Headers | show |
Comments
On Wed, 2009-01-14 at 11:48 -0800, Andrew Klossner wrote: > 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? A few things yes. First, can't you just set the PCI_COMMAND_IO bit from a quirk or at init time rather than adding to code to cope with it being cleared later on ? Also, the fact that it's detected as uninitialized shouldn't have broken access to your device. If there is need for some IO space, for example because a device requests some, the kernel should have re-opened that window of the bridge. Thus if that failed, it would be useful to track it down a bit more. You can try enabling DEBUG in pci-common.c and pci-64.c, boot with "debug" on the kernel command line and and send the resulting dmesg log Ben. > 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; > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-dev
Patch
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;