Re: git: 2f7a796b590e - main - thunderbolt.4: Initial manual for HW Relnotes

On 2025-10-02 12:47 -04:00 EDT, "Mark Millard" <marklmi@yahoo.com> wrote:
> Alexander Ziaee <ziaee_at_FreeBSD.org> wrote on
> Date: Thu, 02 Oct 2025 15:14:07 UTC :
> 
>> The branch main has been updated by ziaee:
>> 
>> URL: https://cgit.FreeBSD.org/src/commit/?id=2f7a796b590e67c5d123f2b00b3aaf7ba7a32a13
>> 
>> commit 2f7a796b590e67c5d123f2b00b3aaf7ba7a32a13
>> Author: Alexander Ziaee <ziaee@FreeBSD.org>
>> AuthorDate: 2025-10-02 12:05:25 +0000
>> Commit: Alexander Ziaee <ziaee@FreeBSD.org>
>> CommitDate: 2025-10-02 15:12:48 +0000
>> 
>> thunderbolt.4: Initial manual for HW Relnotes
>> 
>> This manual contains nothing and is only suitable for the HW Relnotes,
>> but lets get it in so we have something and then can iterate on it.
>> 
>> MFC after: 3 minutes
>> Fixes: 2ed9833791f2 (thunderbolt: Import USB4 code)
>> Discussed with: obiwac
>> Differential Revision: https://reviews.freebsd.org/D52847
>> ---
>> share/man/man4/Makefile | 1 +
>> share/man/man4/thunderbolt.4 | 22 ++++++++++++++++++++++
>> 2 files changed, 23 insertions(+)
>> 
>> diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile
>> index f5d7a0e081fc..6e076722c786 100644
>> --- a/share/man/man4/Makefile
>> +++ b/share/man/man4/Makefile
>> @@ -589,6 +589,7 @@ MAN= aac.4 \
>> tdfx.4 \
>> termios.4 \
>> textdump.4 \
>> + thunderbolt.4 \
>> ti.4 \
>> timecounters.4 \
>> tmpfs.4 \
>> diff --git a/share/man/man4/thunderbolt.4 b/share/man/man4/thunderbolt.4
>> new file mode 100644
>> index 000000000000..3477c11fb60d
>> --- /dev/null
>> +++ b/share/man/man4/thunderbolt.4
>> @@ -0,0 +1,22 @@
>> +.\"
>> +.\" Copyright (c) 2025 Alexander Ziaee
>> +.\"
>> +.\" SPDX-License-Identifier: BSD-2-Clause
>> +.\"
>> +.Dd October 2, 2025
>> +.Dt THUNDERBOLT 4
>> +.Os
>> +.Sh NAME
>> +.Nm thunderbolt
>> +.Nd USB4 controller driver
>> +.Sh SYNOPSIS
>> +.Cd device thunderbolt
>> +.Sh HARDWARE
>> +The
>> +.Nm
>> +driver supports USB4 controllers.
> 
> As I understand things, being fairly explicit related the
> following is likely required (not a proposed wording or
> presentation):
> 
> Quoting USB4 V2: "A USB4 Host or USB4 Peripheral Device can
> optionally support interoperability with Thunderbolt 3
> (TBT3) products."
> 
> Quoting USB4 V1: "A USB4 host or USB4 peripheral device can
> optionally support interoperability with Thunderbolt 3
> (TBT3) products."
> 
> In both, this is tied to Chapter 13, "Interoperability with
> Thunderbolt(tm) 3 systems". As I understand FreeBSD is not
> trying to meet the criteria in that chapter, for example.
> 
> USB4 does not require a certification process, as I
> remember. Thunderbolt 4 and 5 do, as I remember.
> 
> As I remember, a distinction between USB4 and Thunderbolt 4
> and 5 was that Thunderbolt 4 and 5 require (nearly?) all
> optional items from the matching USB4 version to be
> implemented (so: not optional if Thunderbolt 4 or 5 is
> claimed/certified). Also, it seems unlikely that FreeBSD
> would go through a Thunderbolt 4 or 5 certification process.
> 
> Overall this seems to mean not meeting the Thunderbolt 4
> and/or 5 criteria fully and not supporting Thunderbolt 3
> --but just meeting the criteria for one or both of:
> 
> ) USB4 V1 without "TBT3" support
> ) USB4 V2 without "TBT3" support
> 
> That would be a subset of the Thunderbolt 4 or 5 criteria
> in a way that excludes Thunderbolt 3.
> 
> Referencing Thunderbolt without someplace being fairly
> explicit about those types of relationships could easily
> leave a misimpression (even if I've gotten some of the
> status wrong above).
> 
> My guess here is that enough is known about the intent
> in this area to be able to have material about this type
> of thing in place at any time.

My impression is that actually nothing works yet, but we now have a driver called thunderbolt which is made to support these controllers. The driver is in, allegedly, and so it's existence needs to be mentioned in the canonical places where we mention our drivers because people are looking for them for assorted reasons.

Patches to the doc are extremely welcome!

Best,
Alex

>> +.Sh HISTORY
>> +The
>> +.Nm
>> +driver appeared in
>> +.Fx 15.0 .
>> 
> 
> ===
> Mark Millard
> marklmi at yahoo.com
> 
>