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From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Sven Peter <sven@kernel.org>
Cc: Benson Leung <bleung@chromium.org>,
	Abhishek Pandit-Subedi <abhishekpandit@chromium.org>,
	Jameson Thies <jthies@google.com>,
	Andrei Kuchynski <akuchynski@chromium.org>,
	Guenter Roeck <groeck@chromium.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konradybcio@kernel.org>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [PATCH] usb: typec: tbt: Correct swapped TBT adapter type values
Date: Wed, 26 Aug 2026 06:21:43 +0000	[thread overview]
Message-ID: <ao6F9_7DfZx-xNNJ@google.com> (raw)
In-Reply-To: <20260818-b4-tbt-legacy-fix-v1-1-797831e3df3f@kernel.org>

On Tue, Aug 18, 2026 at 06:20:03PM +0200, Sven Peter wrote:
> Table F-10 of the USB Type-C Cable and Connector Specification R2.5 on
> page 412 defines bit 16 of the TBT3 Device Discover Mode VDO as 0 = TBT3
> Adapter and 1 = TBT2 Legacy Adapter. Linux has those two swapped since
> their original introduction in commit ca469c292edc ("usb: typec: Add
> definitions for Thunderbolt 3 Alternate Mode").
> 
> ChromiumOS EC's include/usb_pd_tbt.h has them the correct way around
> and references the USB Type-C ECN "Thunderbolt 3 Compatibility Updates"
> as fixing an error where they were originally swapped which is presumably
> where the wrong order originally came from.
> 
> I've also confirmed the correct mapping with an Apple Thunderbolt 3
> to Thunderbolt 2 adapter which does set bit 16 in that VDO.
> 
> Swap the two values and update all users. Also rename the old defines
> so that no user accidentally ends up with an inverted value.
> No functional change.
> 
> Link: https://usb.org/document-library/usb-type-cr-cable-and-connector-specification-release-25
> Link: https://chromium.googlesource.com/chromiumos/platform/ec/+/db93814b6e73c8545d23714fe0674c10814d901a/include/usb_pd_tbt.h#90
> Signed-off-by: Sven Peter <sven@kernel.org>
...
>  drivers/platform/chrome/cros_ec_typec.c | 2 +-

For cros_ec_typec.c,
Acked-by: Tzung-Bi Shih <tzungbi@kernel.org>

      parent reply	other threads:[~2026-08-26  6:21 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-18 16:20 [PATCH] usb: typec: tbt: Correct swapped TBT adapter type values Sven Peter
2026-08-19 10:34 ` Konrad Dybcio
2026-08-24 11:11 ` Heikki Krogerus
2026-08-24 11:31   ` Sven Peter
2026-08-26  6:21 ` Tzung-Bi Shih [this message]

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