@@ -170,7 +170,7 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
{
u32 l, sz, mask;
u16 orig_cmd;
- struct pci_bus_region region;
+ struct pci_bus_region region, inverted_region;
bool bar_too_big = false, bar_disabled = false;
mask = type ? PCI_ROM_ADDRESS_MASK : ~0;
@@ -267,6 +267,29 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
pcibios_bus_to_resource(dev, res, ®ion);
+ /*
+ * In some situations, the bus and memory address used by kernel are
+ * not equal and the firmware may assign a bus address which happen
+ * to be a legitimate memory address to a PCI device, then the kernel
+ * would not find a matching bus region in host bridge and assume an
+ * offset of zero and translate it to a memory address the same as the
+ * bus address. This will leave the bus address in the PCI BAR register
+ * unchanged and this address is definitely not a legal bus address,
+ * then cause the device malfunction. We try to detect this by doing
+ * a invert translation. We can make sure that we run into this case
+ * if the value we get from the invert translation is not equal to the
+ * original bus address.
+ */
+ pcibios_resource_to_bus(dev, &inverted_region, res);
+ if (inverted_region.start != region.start ||
+ inverted_region.end != region.end) {
+ dev_info(&dev->dev, "reg 0x%x: bus address [%pa - %pa] allocated by firmware is not in any of the address regions of PCI host bridge, we would force to reassign it later\n",
+ pos, ®ion.start, ®ion.end);
+ res->flags |= IORESOURCE_UNSET;
+ res->end -= res->start;
+ res->start = 0;
+ }
+
goto out;
In some situations, the bus and memory address used by kernel are not equal and the firmware may assign a bus address which happen to be a legitimate memory address to a PCI device, then the kernel would not find a matching bus region in host bridge and assume an offset of zero and translate it to a memory address the same as the bus address. This will leave the bus address in the PCI BAR register unchanged and this address is definitely not a legal bus address, then cause the device malfunction. We try to detect this by doing a invert translation. We can make sure that we run into this case if the value we get from the invert translation is not equal to the original bus address. In this case we would unset this resource and wish the kernel would trigger a reassign later. Signed-off-by: Kevin Hao <haokexin@gmail.com> --- v2: Instead of tweak the pcibios_bus_to_resource and assume we know about all the host bridge window, we do an invert translation to check if we have a wrong bus address set in the PCI BAR register. drivers/pci/probe.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)