Please backport the following commit into Linux v5.4 and newer stable releases:

80dc18a0cba8dea42614f021b20a04354b213d86

The backport will likely depend on macro rename commit:

817f989700fddefa56e5e443e7d138018ca6709d

This part of commit description clarifies why this is a fix:

" As per PCIe r6.0, sec 6.6.1, a Downstream Port that supports Link speeds greater than 5.0 GT/s, software must wait a minimum of 100 ms after Link training completes before sending a Configuration Request. "

In practice, this makes detection of PCIe Gen3 and Gen4 SSDs reliable on Renesas R-Car V4H SoC. Without this commit, the SSDs sporadically do not get detected, or sometimes they link up in Gen1 mode.

This fixes commit

886bc5ceb5cc ("PCI: designware: Add generic dw_pcie_wait_for_link()")

which is in v4.5-rc1-4-g886bc5ceb5cc3 , so I think this fix should be backported to all currently maintained stable releases, i.e. v5.4+ .

Thank you