Writing the PCI memory base & limit registers leads to the root bridge reporting a PCI_MEMORY_BASE value of 0 & a PCI_MEMORY_LIMIT value of 0x1600. If we then boot Linux, it sees that the bridge device needs 0x16000000 bytes of memory space & fails to assign it.
It's unclear to me why this happens, and poking values from the shell doesn't seem to make anything clearer, but this workaround allows a MIPS Boston board to boot Linux & let Linux successfully probe the PCIe bus & all devices connected to it.
Signed-off-by: Paul Burton paul.burton@imgtec.com ---
drivers/pci/pcie_xilinx.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/pci/pcie_xilinx.c b/drivers/pci/pcie_xilinx.c index 9059c41..0237bec 100644 --- a/drivers/pci/pcie_xilinx.c +++ b/drivers/pci/pcie_xilinx.c @@ -160,6 +160,15 @@ static int pcie_xilinx_write_config(struct udevice *bus, pci_dev_t bdf, if (err < 0) return 0;
+ if (bdf == PCI_BDF(bus->seq, 0, 0)) { + switch (offset) { + case PCI_MEMORY_BASE: + case PCI_MEMORY_LIMIT: + /* Writing the memory base or limit causes problems */ + return 0; + } + } + switch (size) { case PCI_SIZE_8: __raw_writeb(value, address);