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Date:   Tue, 24 Jul 2018 22:22:40 +0200
From:   Wolfram Sang <wsa@the-dreams.de>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Peter Rosin <peda@axentia.se>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Linux I2C <linux-i2c@vger.kernel.org>,
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        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Przemyslaw Sroka <psroka@cadence.com>,
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        Alan Douglas <adouglas@cadence.com>,
        Bartosz Folta <bfolta@cadence.com>,
        Damian Kos <dkos@cadence.com>,
        Alicja Jurasik-Urbaniak <alicja@cadence.com>,
        Cyprian Wronka <cwronka@cadence.com>,
        Suresh Punnoose <sureshp@cadence.com>,
        Rafal Ciepiela <rafalc@cadence.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
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        Sekhar Nori <nsekhar@ti.com>, Przemyslaw Gaj <pgaj@cadence.com>
Subject: Re: [PATCH v6 00/10] Add the I3C subsystem
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> > My personal use case is debugging. R-Car H2 is great because I can
> > always pinmux this or that I2C IP core to the same set of pins, and in 2
> > out of 4 cases even GPIO bitbang on top of that. So, it is great to
> > compare behaviour, do scopes with the same type of setup, etc...
> > For that, I do runtime switches, but the slaves are not really under
> > real usage.
>=20
> Ok, so runtime here still means it's chosen by an operator (i.e. you),
> not part of regular operation.

Yes.

> I meant multiplexing it through the pinmux framework, with one of the
> two being active at any time. Obviously this makes no sense for
> i3c slaves, but it can be useful if the bus only contains i2c slaves.

Unless Linux is not an I2C slave itself.

> What I meant here was switching the bus between an i2c master and an
> i3c master like you do with the i2c demuxer. Right now, this wouldn't
> work because i2c and i3c use different representations in DT and in
> Linux for the same devices.

I see. Thanks for the clarification.


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