On Thu, Mar 31, 2022 at 12:53:45PM +0100, Dimitri John Ledkov wrote:
From: Ben Dooks ben.dooks@codethink.co.uk
commit a382c757ec5ef83137a86125f43a4c43dc2ab50b upstream.
The fu740 PCIe core does not probe any devices on the SiFive Unmatched board without this fix (or having U-Boot explicitly start the PCIe via either boot-script or user command). The fix is to start the link at 2.5GT/s speeds and once the link is up then change the maximum speed back to the default.
The U-Boot driver claims to set the link-speed to 2.5GT/s to get the probe to work (and U-Boot does print link up at 2.5GT/s) in the following code: https://source.denx.de/u-boot/u-boot/-/blob/master/drivers/pci/pcie_dw_sifiv...
Link: https://lore.kernel.org/r/20220318152430.526320-1-ben.dooks@codethink.co.uk Signed-off-by: Ben Dooks ben.dooks@codethink.co.uk Signed-off-by: Bjorn Helgaas bhelgaas@google.com Acked-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Dimitri John Ledkov dimitri.ledkov@canonical.com
Please apply this patch to v5.15+ stable trees which fixes PCIe on the very popular SiFive Unmatched RISC-V board.
drivers/pci/controller/dwc/pcie-fu740.c | 51 ++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-)
Now queued up, thanks.
greg k-h