On Monday, April 20, 2015 06:30:55 PM Bjorn Helgaas wrote:
> Prior to c770cb4cb505 ("PCI: Mark invalid BARs as unassigned"), if we tried
> to claim a PCI BAR but could not find an upstream bridge window that
> matched it, we complained but still allowed the device to be enabled.
>
> c770cb4cb505 broke devices that previously worked (mptsas and igb in the
> case Tony reported, but it could be any devices) because it marks those
> BARs as IORESOURCE_UNSET, which makes pci_enable_device() complain and
> return failure:
>
> igb 0000:81:00.0: can't enable device: BAR 0 [mem size 0x00020000] not assigned
> igb: probe of 0000:81:00.0 failed with error -22
>
> The underlying cause is an ACPI Address Space Descriptor for a PCI host
> bridge window that is marked as "consumer". This is a firmware defect:
> resources that are produced on the downstream side of a bridge should be
> marked "producer". But rejecting these BARs that we previously allowed is
> a functionality regression, and firmware has not used the producer/consumer
> bit consistently, so we can't rely on it anyway.
>
> Stop checking the producer/consumer bit, and assume all bridge Address
> Space Descriptors are for bridge windows.
>
> Note that this change does not affect I/O Port or Fixed Location I/O Port
> Descriptors, which are commonly used for the [io 0x0cf8-0x0cff] config
> access range. That range is a "consumer" range and should not be treated
> as a window.
>
> Fixes: c770cb4cb505 ("PCI: Mark invalid BARs as unassigned")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=96961
> Reported-and-tested-by: Tony Luck <tony.luck@xxxxxxxxx>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
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