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Message-ID: <20221107124055.0495031f@booty>
Date: Mon, 7 Nov 2022 12:40:55 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Andy Shevchenko <andriy.shevchenko@...el.com>,
devicetree@...r.kernel.org, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
Hans Verkuil <hverkuil-cisco@...all.nl>,
Jacopo Mondi <jacopo@...ndi.org>,
Kieran Bingham <kieran.bingham@...asonboard.com>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Luca Ceresoli <luca@...aceresoli.net>,
Mark Rutland <mark.rutland@....com>,
Matti Vaittinen <Matti.Vaittinen@...rohmeurope.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Peter Rosin <peda@...ntia.se>,
Rob Herring <robh+dt@...nel.org>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Vladimir Zapolskiy <vz@...ia.com>,
Wolfram Sang <wsa@...-dreams.de>,
satish.nagireddy@...cruise.com
Subject: Re: [PATCH v4 2/8] i2c: add I2C Address Translator (ATR) support
On Fri, 4 Nov 2022 13:59:06 +0200
Tomi Valkeinen <tomi.valkeinen@...asonboard.com> wrote:
> Hi Andy,
>
> On 01/11/2022 16:30, Andy Shevchenko wrote:
> > On Tue, Nov 01, 2022 at 03:20:26PM +0200, Tomi Valkeinen wrote:
> >> From: Luca Ceresoli <luca@...aceresoli.net>
> >>
> >> An ATR is a device that looks similar to an i2c-mux: it has an I2C
> >> slave "upstream" port and N master "downstream" ports, and forwards
> >> transactions from upstream to the appropriate downstream port. But is
> >> is different in that the forwarded transaction has a different slave
> >> address. The address used on the upstream bus is called the "alias"
> >> and is (potentially) different from the physical slave address of the
> >> downstream chip.
> >>
> >> Add a helper file (just like i2c-mux.c for a mux or switch) to allow
> >> implementing ATR features in a device driver. The helper takes care or
> >> adapter creation/destruction and translates addresses at each transaction.
First of all, thank you for bringing this work on!
> > ...
> >
> >> +I2C ADDRESS TRANSLATOR (ATR)
> >> +M: Luca Ceresoli <luca@...aceresoli.net>
> >
> > Hmm... Are you going to maintain this? Or Review? Why not?
>
> We haven't discussed with Luca if he wants to maintain this (this is
> mostly his code). But, indeed, I should add my name there.
I think at this point you are probably in a better position to be the
maintainer, but I'm OK with being listed here as reviewer (R:).
Ah, would you please use my bootlin dot com address here?
> I'm not arguing against any of the comments you've made, I think they
> are all valid, but I want to point out that many of them are in a code
> copied from i2c-mux.
>
> Whether there's any value in keeping i2c-mux and i2c-atr similar in
> design/style... Maybe not.
Tomi is right, when I wrote this initially I tried to keep it as
similar as possible to i2c-mux.c. No problem in deviating from that
wherever it makes sense.
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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