Re: [PATCH v3 19/36] thunderbolt: Extend tunnel creation to more than 2 adjacent switches

[Mika Westerberg]

On Mon, Apr 08, 2019 at 10:53:37AM +0200, Lukas Wunner wrote:
> Hm, what other cases are there, i.e. what is the meaning of a tb_regs_hop's
> "next_hop" field if "out_port" doesn't have a remote?  (And why does it
> need to be tracked on the out_port?  In case a remote is added later?)

We also need to program HopIDs for adapter ports (PCIe, DP, NHI) in
order to enable a path. The "next_hop" from NULL port to an adapter port
tells the HopID a packet gets when it is routed to the adapter port and
the adapter port registers then are used to specify which HopID means
what (for PCIe there is only 8 but for DP there is 8 and 9, for NHI it
can be anything the service driver has negotiated).