[Skiboot] [PATCH 1/3] core/pci: Fix lost NVMe adapter behind PMC 8546 switch

[Gavin Shan]

On Wed, Mar 22, 2017 at 02:03:59PM +1100, Gavin Shan wrote:
>The NVMe adapter in below PCI topology is lost. The root cause is
>the presence bit on its PCI slot is missed, but the PCIe link has
>been up. The PCI core doesn't probe the adapter behind the slot,
>leading to lost NVMe adapter in the particular case.
>
>   PHB3 root port
>   PLX switch 8748 (10b5:8748)
>   PLX swich 9733 (10b5:9733)
>   PMC 8546 swtich (11f8:8546)
>   NVMe adapter (1c58:0023)
>
>This fixes the issue by overriding the PCI slot presence bit with
>PCIe link state bit.
>
>Reported-by: Mark E Schreiter <markes at us.ibm.com>
>Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>

Please hold for merging. With PATCH[2/3] and PATCH[3/3] applied,
The samsung NVMe adapter is still missed when it's connected to
PMC PCIe switch. For this case, the proper fix would be to disable
the CRC generation/check on the root port, not on the endpoints.
I'll rework PATCH[2/3] and PATCH[3/3] and post an updated version.

Thanks,
Gavin