Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 30 Jun 2022 13:18:33 +0300
From:   Mika Westerberg <mika.westerberg@linux.intel.com>
To:     Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc:     Prashant Malani <pmalani@chromium.org>,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        chrome-platform@lists.linux.dev, bleung@chromium.org,
        Daisuke Nojiri <dnojiri@chromium.org>,
        "Dustin L. Howett" <dustin@howett.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Guenter Roeck <groeck@chromium.org>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Sebastian Reichel <sebastian.reichel@collabora.com>
Subject: Re: [PATCH 1/9] usb: typec: Add support for retimers
Message-ID: <Yr14eZexhvvrWrOS@lahna>
References: <20220629233314.3540377-1-pmalani@chromium.org>
 <20220629233314.3540377-2-pmalani@chromium.org>
 <Yr1cN1I14BR6rN3U@kuha.fi.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Yr1cN1I14BR6rN3U@kuha.fi.intel.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
Precedence: bulk

On Thu, Jun 30, 2022 at 11:17:59AM +0300, Heikki Krogerus wrote:
> On Wed, Jun 29, 2022 at 11:32:19PM +0000, Prashant Malani wrote:
> > Introduce a retimer device class and associated functions that register
> > and use retimer "switch" devices. These operate in a manner similar to
> > the "mode-switch" and help configure retimers that exist between the
> > Type-C connector and host controller(s).
> > 
> > Type C ports can be linked to retimers using firmware node device
> > references (again, in a manner similar to "mode-switch").
> > 
> > Signed-off-by: Prashant Malani <pmalani@chromium.org>
> 
> Cool! This looks really good to me.
> 
> I'll add Mika here, just to keep him in the loop. Thunderbolt/USB4 can
> control the same physical retimers over the SBU line. Right now there
> is no conflict, but I think we want to later be able to use these
> devices to upgrade the retimer firmware, and that is something that
> the Thunderbolt/USB4 already does. So let's keep an eye on this.
> 
> I wonder, would it make sense to later make the thunderbolt_retimer
> devices also part of the device class that's introduced here? I think
> that way it would be easier to later figure out which
> thunderbolt_retimer and which retimer_switch represent the same
> physical retimer. And perhaps it would also be more clear for the user
> space to have a single device class for the retimers?

I agree this makes sense.