[Skiboot] PCIe training failure on PLX PCI bridge

[Oliver]

On Thu, Jun 6, 2019 at 2:24 PM Timothy Pearson
<tpearson at raptorengineering.com> wrote:
>
> Popped in a couple of new tuner cards into our "oddball hardware"
> testing unit (Talos II w/ two P9 DD2.2 CPUs).  These use a Pericom
> bridge chip, PI7C9X2G304, as the PCIe interface.
>
> The links train but are degraded so are taken back offline.  Both cards
> are brand new and show the exact same problem.

What skiboot version are you using? The workaround in 02a683bf09d9
("hw/phb4: Assert Link Disable bit after ETU init") might help.

> Log from PHB#0 in Mata mode:

Mata mode doesn't appear to be enabled since there's no TRACE: lines
in the output. Turn on the link trace output with:

nvram -p ibm,skiboot --update-config pci-tracing=true

It should look something like this:

     PHB#0001[0:1]: TRACE:0x0000102101000000  0ms presence GEN1:x16:polling
     PHB#0001[0:1]: TRACE:0x0000001101000000 23ms          GEN1:x16:detect
     PHB#0001[0:1]: TRACE:0x0000102101000000 23ms presence GEN1:x16:polling
     PHB#0001[0:1]: TRACE:0x0000183101000000 29ms training GEN1:x16:config
     PHB#0001[0:1]: TRACE:0x00001c5881000000 30ms training GEN1:x08:recovery
     PHB#0001[0:1]: TRACE:0x00001c5883000000 30ms training GEN3:x08:recovery
     PHB#0001[0:1]: TRACE:0x0000144883000000 33ms presence GEN3:x08:L0
     PHB#0001[0:1]: TRACE:0x0000154883000000 33ms trained  GEN3:x08:L0