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From: Arnd Bergmann <arnd@arndb.de>
To: Peter Rosin <peda@axentia.se>
Cc: Boris Brezillon <boris.brezillon@bootlin.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	linux-i2c@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Przemyslaw Sroka <psroka@cadence.com>,
	Arkadiusz Golec <agolec@cadence.com>,
	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>,
	Kumar Gala <galak@codeaurora.org>,
	DTML <devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Vitor Soares <Vitor.Soares@synopsys.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Xiang Lin <Xiang.Lin@synaptics.com>,
	linux-gpio@vger.kernel.org
Subject: Re: [PATCH v4 01/10] i3c: Add core I3C infrastructure
Date: Thu, 12 Jul 2018 10:08:05 +0200	[thread overview]
Message-ID: <CAK8P3a2oMDw2zHzE5vFFHDqzKVKEzOga6v0ExdYVawnMtcdbrQ@mail.gmail.com> (raw)
In-Reply-To: <a31dc625-56bf-7a59-d9a3-2841360b864e@axentia.se>

On Thu, Jul 12, 2018 at 6:41 AM, Peter Rosin <peda@axentia.se> wrote:
> On 2018-07-11 19:12, Boris Brezillon wrote:
>> On Wed, 11 Jul 2018 17:39:56 +0200 Arnd Bergmann <arnd@arndb.de> wrote:
>>
>> That's exactly the sort of discussion I wanted to trigger. Maybe we
>> shouldn't care and expose this use case as if it was X different I3C
>> buses (with all devices present on the bus being exposed X times to the
>> system).
>
> For I2C, this multiple masters for one bus case was retrofitted in
> the i2c-demux-pinctrl driver. It's a huge kludge with a number of
> undesirable quirks. I don't know if the circumstances for adding
> this I2C driver also applies for I3C, but it might be an argument
> in favor of the proposed extra bus object...

From reading the documentation and git history on that driver,
it seems to be used only for static configuration, i.e. you use
one driver or the other, but don't flip between them at runtime,
right?

I'm guessing that even with i3c we may have to support something
like that, as a likely scenario might be that the i3c controller is
multiplexed with a traditional i2c controller and/or gpios, but you
would not be able to perform the i3c standard secondary master
transition with the latter two because they are (by definition) not
i3c compatible.

       Arnd

  parent reply	other threads:[~2018-07-12  8:08 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-30  7:47 [PATCH v4 00/10] Add the I3C subsystem Boris Brezillon
2018-03-30  7:47 ` [PATCH v4 01/10] i3c: Add core I3C infrastructure Boris Brezillon
2018-06-04  9:11   ` Przemyslaw Gaj
2018-06-04 11:24     ` Boris Brezillon
2018-06-14  4:19   ` Wolfram Sang
2018-06-14  7:07     ` Boris Brezillon
2018-06-14  8:15       ` Wolfram Sang
2018-06-20 11:37   ` Sekhar Nori
2018-06-20 12:47     ` Boris Brezillon
2018-07-11 14:01   ` Arnd Bergmann
2018-07-11 14:41     ` Boris Brezillon
2018-07-11 15:03       ` Boris Brezillon
2018-07-11 15:39       ` Arnd Bergmann
2018-07-11 17:12         ` Boris Brezillon
2018-07-11 20:10           ` Arnd Bergmann
2018-07-11 22:09             ` Boris Brezillon
2018-07-12  8:21               ` Arnd Bergmann
2018-07-12  8:46                 ` Boris Brezillon
2018-07-12 10:03                   ` Arnd Bergmann
2018-07-12 10:24                     ` Boris Brezillon
2018-07-12  4:41           ` Peter Rosin
2018-07-12  8:04             ` Boris Brezillon
2018-07-12  8:08             ` Arnd Bergmann [this message]
2018-07-12  8:44               ` Peter Rosin
2018-03-30  7:47 ` [PATCH v4 02/10] docs: driver-api: Add I3C documentation Boris Brezillon
2018-03-30  7:47 ` [PATCH v4 03/10] i3c: Add sysfs ABI spec Boris Brezillon
2018-04-29 13:37   ` Greg Kroah-Hartman
2018-04-30  9:10     ` Boris Brezillon
2018-05-02  9:47     ` Geert Uytterhoeven
2018-05-02 11:10       ` Greg Kroah-Hartman
2018-05-02 11:32         ` Geert Uytterhoeven
2018-03-30  7:47 ` [PATCH v4 04/10] dt-bindings: i3c: Document core bindings Boris Brezillon
2018-03-30  7:55   ` Geert Uytterhoeven
2018-03-30  7:59     ` Boris Brezillon
2018-04-09 20:24   ` Rob Herring
2018-03-30  7:47 ` [PATCH v4 05/10] dt-bindings: i3c: Add macros to help fill I3C/I2C device's reg property Boris Brezillon
2018-03-30  7:47 ` [PATCH v4 06/10] MAINTAINERS: Add myself as the I3C subsystem maintainer Boris Brezillon
2018-03-30  7:47 ` [PATCH v4 07/10] i3c: master: Add driver for Cadence IP Boris Brezillon
2018-06-04  9:24   ` Przemyslaw Gaj
2018-06-04 11:26     ` Boris Brezillon
2018-03-30  7:47 ` [PATCH v4 08/10] dt-bindings: i3c: Document Cadence I3C master bindings Boris Brezillon
2018-04-09 20:25   ` Rob Herring
2018-03-30  7:47 ` [PATCH v4 09/10] gpio: Add a driver for Cadence I3C GPIO expander Boris Brezillon
2018-04-26  8:44   ` Linus Walleij
2018-06-22  8:24     ` Boris Brezillon
2018-03-30  7:47 ` [PATCH v4 10/10] dt-bindings: gpio: Add bindings for Cadence I3C gpio expander Boris Brezillon
2018-04-09 20:26   ` Rob Herring
2018-04-23 17:38 ` [PATCH v4 00/10] Add the I3C subsystem Boris Brezillon
2018-04-23 17:56   ` Greg Kroah-Hartman
2018-04-29 13:36     ` Greg Kroah-Hartman
2018-04-30  9:37       ` Boris Brezillon

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