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Date:   Mon, 26 Dec 2022 21:25:34 +0200
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Subject: Re: [PATCH v5 7/8] media: i2c: add DS90UB913 driver
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Wolfram Sang <wsa@kernel.org>,
        Luca Ceresoli <luca.ceresoli@bootlin.com>,
        Andy Shevchenko <andriy.shevchenko@intel.com>,
        Matti Vaittinen <Matti.Vaittinen@fi.rohmeurope.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Peter Rosin <peda@axentia.se>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Michael Tretter <m.tretter@pengutronix.de>,
        Shawn Tu <shawnx.tu@intel.com>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Mike Pagano <mpagano@gentoo.org>,
        =?UTF-8?Q?Krzysztof_Ha=c5=82asa?= <khalasa@piap.pl>,
        Marek Vasut <marex@denx.de>
References: <20221208104006.316606-1-tomi.valkeinen@ideasonboard.com>
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From:   Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
In-Reply-To: <Y6nSVlmlweUuUwJf@pendragon.ideasonboard.com>
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On 26/12/2022 18:56, Laurent Pinchart wrote:
> Hi Tomi,
> 
> On Wed, Dec 14, 2022 at 08:36:47AM +0200, Tomi Valkeinen wrote:
>> On 14/12/2022 08:29, Tomi Valkeinen wrote:
>>
>>>> wondering if the struct device of the DS90UB913 could be passed instead
>>>> of the port, to avoid passing the port throught
>>>> ds90ub9xx_platform_data.
>>>
>>> Interesting thought. That would limit the number of remote i2c busses to
>>> one, though. Not a problem for FPD-Link, but I wonder if that's assuming
>>> too much for the future users. Then again, this is an in-kernel API so
>>> we could extend it later if needed. So I'll try this out and see if I
>>> hit any issues.
>>
>> Right, so the issue with this one would be that it would prevent a
>> single device uses. E.g. a single chip which acts as an ATR (similar to
>> i2c-mux chips), i.e. it contains both the main and the remote i2c busses.
> 
> I don't think I understand this, sorry.

What you are suggesting above means that we'd have a separate device for 
each port of the ATR. Which is fine in our current case, as the i2c 
master busses are behind separate remote devices.

But if you consider a case similar to i2c-mux, where we have a single 
chip with the slave bus and, say, 4 master busses. We would probably 
have only a single device for that.

  Tomi