Re: [PATCH] usb: typec: tbt: Correct swapped TBT adapter type values

[Sven Peter]

On 8/24/26 13:11, Heikki Krogerus wrote:
> 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@xxxxxxxxxx>
> Shouldn't this be marked as a fix?

I left it out deliberately together with Cc: stable because there's no 
functional change but I can just add it if you want to. The original 
commit is already in the message.
> Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

Thanks!


Sven