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Date:   Mon, 8 Apr 2019 12:07:44 +0300
From:   Mika Westerberg <mika.westerberg@linux.intel.com>
To:     Lukas Wunner <lukas@wunner.de>
Cc:     linux-kernel@vger.kernel.org,
        Michael Jamet <michael.jamet@intel.com>,
        Yehezkel Bernat <YehezkelShB@gmail.com>,
        Andreas Noever <andreas.noever@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Christian Kellner <ckellner@redhat.com>,
        Mario.Limonciello@dell.com
Subject: Re: [PATCH v3 19/36] thunderbolt: Extend tunnel creation to more
 than 2 adjacent switches
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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).