rk3399 - Rock Pi 4 PCIe

[Anthony Davies]

Hi All,

I have applied Jagan's PCIe patch for Rockchip (
http://lists.infradead.org/pipermail/linux-rockchip/2020-May/031117.html)
to my Rock Pi 4 but I am getting intermittent results with the PCIe bus
(and hence NVMe m.2) showing in u-boot (and then Linux).

When it is successful the pci command shows the pci bus as expected when it
isnt working I get the following:
=> pci
PCIe link training gen1 timeout!
No such bus
=> pci enum
failed to find ep-gpios property
=> fatload mmc 0:4 ${fdt_addr_r} rk3399-rock-pi-4.dtb
54702 bytes read in 21 ms (2.5 MiB/s)
=> fdt addr ${fdt_addr_r}
=> fdt set /pcie at f8000000 ep-gpios  <0xb7 27 0>
=> fdt print /pcie at f8000000 ep-gpios
ep-gpios = <0x000000b7 0x0000001b 0x00000000>
=> pci
failed to find ep-gpios property
No such bus
=> pci enum
failed to find ep-gpios property

I have 4 of these boards with the same intermittent results on all of them.
It fails more then it succeeds and I have a combination of both booted into
linux on my network at the moment.

When researching the issue I did see some commentary on a timing issue
between training and bus scanning on rockchip and I am not sure if this is
relevant to my problem.

Would appreciate any insights people may have and am very happy to work
with people to troubleshoot the issue.

Cheers,

Tony