On 18/03/2022 15:21, Ben Dooks wrote:
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_sifive.c?id=v2022.01#L271 Signed-off-by: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> -- Note, this patch has had significant re-work since the previous 4 sets, including trying to fix style, message, reliance on the U-Boot fix and the comments about usage of LINK_CAP and reserved fields.
Apologies, it seems I forgot to do "git commit --amend" on the last file save. I've now sent a "V3" -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius https://www.codethink.co.uk/privacy.html
