Re: [PATCH v2 4/4] Documentation/admin-guide: Document Thunderbolt/USB4 tunneling events

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Apr 17, 2025 at 12:04:26PM +0300, Mika Westerberg wrote:
> From: Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>
> 
> Add documentation about the Thunderbolt/USB4 tunneling events to the
> user’s and administrator’s guide.
> 
> Signed-off-by: Alan Borzeszkowski <alan.borzeszkowski@linux.intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
>  Documentation/admin-guide/thunderbolt.rst | 33 +++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst
> index d0502691dfa1..f0368ab6bd1f 100644
> --- a/Documentation/admin-guide/thunderbolt.rst
> +++ b/Documentation/admin-guide/thunderbolt.rst
> @@ -296,6 +296,39 @@ information is missing.
>  To recover from this mode, one needs to flash a valid NVM image to the
>  host controller in the same way it is done in the previous chapter.
>  
> +Tunneling events
> +----------------
> +The driver sends ``KOBJ_CHANGE`` events to userspace when there is a
> +tunneling change in the ``thunderbolt_domain``. The notification carries
> +following environment variables::
> +
> +  TUNNEL_EVENT=<EVENT>
> +  TUNNEL_DETAILS=0:12 <-> 1:20 (USB3)

I'm ok with this, but wow TUNNEL_DETAILS is going to be hard to parse by
userspace, right?  Is this something that it is supposed to do something
with?

thanks,

greg k-h