From: Peter Rosin <peda@axentia.se>
To: Arnd Bergmann <arnd@arndb.de>, Wolfram Sang <wsa@the-dreams.de>
Cc: Boris Brezillon <boris.brezillon@bootlin.com>,
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+devicetr>
Subject: Re: [PATCH v6 00/10] Add the I3C subsystem
Date: Fri, 20 Jul 2018 13:13:49 +0200 [thread overview]
Message-ID: <21b269c5-a3a7-c5de-c81e-c9c9301ae13e@axentia.se> (raw)
In-Reply-To: <CAK8P3a2Pqo5DuYBb09+w4nGWGOw+e_tZPxnA06qjNO_6Hw6NvQ@mail.gmail.com>
On 2018-07-20 12:57, Arnd Bergmann wrote:
> * What I understand from reading i2c-demux-pinctrl.c, a slave device
> will only ever be observable from one master at a time, when you
> switch over, all children get removed on one master and added to
> the other one, to be probed again by their respective drivers.
> I can see this as a useful feature on i3c as well, in particular to
> deal with the situation where we have i2c slaves connected to a
> pinmux that can switch them between an i3c master and an
> i2c-only master (possibly a gpio based one). That particular use
> case however doesn't seem to fix well in the current code, which
> is structure around i3c buses.
It's pretty easy to come up with examples where this reprobing is
not desirable at all. E.g. if one of the involved I2C devices is
a HDMI encoder (I have a TDA19988 here) sitting in the middle of the
graphics pipeline. Blink-blink on the screen because some *other*
unrelated device needed to be accessed by an alternative master. Not
pretty.
(No, I don't suffer from this since I don't need the demuxer. Which is
fortunate. This was just an example, I'm sure there are others.)
Cheers,
Peter
next prev parent reply other threads:[~2018-07-20 11:13 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-19 15:29 [PATCH v6 00/10] Add the I3C subsystem Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 01/10] i3c: Add core I3C infrastructure Boris Brezillon
2018-08-03 21:38 ` mshettel
2018-08-04 5:33 ` Boris Brezillon
2018-08-22 16:43 ` vitor
2018-08-24 12:39 ` Boris Brezillon
2018-08-24 17:52 ` vitor
2018-08-24 18:16 ` Boris Brezillon
2018-08-28 11:50 ` vitor
2018-08-28 12:02 ` Boris Brezillon
2018-08-28 12:55 ` Przemyslaw Gaj
2018-08-28 13:01 ` Boris Brezillon
2018-08-29 7:41 ` Przemyslaw Gaj
2018-08-28 13:03 ` Boris Brezillon
2018-08-30 13:57 ` vitor
2018-08-30 19:00 ` Przemyslaw Gaj
2018-09-03 9:33 ` vitor
2018-09-04 11:03 ` Przemyslaw Gaj
2018-09-06 12:43 ` Przemyslaw Gaj
2018-09-06 12:59 ` Arnd Bergmann
2018-09-06 13:14 ` Boris Brezillon
2018-09-06 13:20 ` Boris Brezillon
2018-09-06 13:45 ` Arnd Bergmann
2018-09-06 13:50 ` vitor
2018-09-06 14:14 ` Boris Brezillon
2018-09-06 15:17 ` vitor
2018-09-06 16:06 ` Boris Brezillon
2018-09-06 16:17 ` Przemyslaw Gaj
2018-09-10 16:16 ` vitor
2018-09-07 7:51 ` Przemyslaw Gaj
2018-09-06 13:47 ` Przemyslaw Gaj
2018-09-06 14:09 ` Boris Brezillon
2018-09-06 14:20 ` Przemyslaw Gaj
2018-07-19 15:29 ` [PATCH v6 02/10] docs: driver-api: Add I3C documentation Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 03/10] i3c: Add sysfs ABI spec Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 04/10] dt-bindings: i3c: Document core bindings Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 05/10] dt-bindings: i3c: Add macros to help fill I3C/I2C device's reg property Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 06/10] MAINTAINERS: Add myself as the I3C subsystem maintainer Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 07/10] i3c: master: Add driver for Cadence IP Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 08/10] dt-bindings: i3c: Document Cadence I3C master bindings Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 09/10] gpio: Add a driver for Cadence I3C GPIO expander Boris Brezillon
2018-07-19 15:29 ` [PATCH v6 10/10] dt-bindings: gpio: Add bindings for Cadence I3C gpio expander Boris Brezillon
2018-07-20 8:52 ` [PATCH v6 00/10] Add the I3C subsystem Arnd Bergmann
2018-07-20 9:57 ` Peter Rosin
2018-07-20 10:05 ` Boris Brezillon
2018-07-20 10:39 ` Peter Rosin
2018-07-20 10:12 ` Wolfram Sang
2018-07-20 10:57 ` Arnd Bergmann
2018-07-20 11:05 ` Wolfram Sang
2018-07-20 11:13 ` Peter Rosin [this message]
2018-07-20 11:28 ` Arnd Bergmann
2018-07-20 13:16 ` Peter Rosin
2018-07-20 15:41 ` Wolfram Sang
2018-07-24 14:14 ` Arnd Bergmann
2018-07-24 15:57 ` Wolfram Sang
2018-07-24 16:04 ` Arnd Bergmann
2018-07-24 20:22 ` Wolfram Sang
2018-07-24 16:07 ` Boris Brezillon
2018-07-20 13:17 ` Boris Brezillon
2018-07-24 14:03 ` Arnd Bergmann
2018-07-24 14:28 ` Boris Brezillon
2018-07-24 15:05 ` Arnd Bergmann
2018-07-24 15:15 ` Geert Uytterhoeven
2018-07-24 15:40 ` Arnd Bergmann
2018-07-24 15:46 ` Geert Uytterhoeven
2018-07-24 15:58 ` Arnd Bergmann
2018-07-24 16:14 ` Boris Brezillon
2018-07-24 16:25 ` Arnd Bergmann
2018-07-24 16:54 ` Boris Brezillon
2018-07-24 20:21 ` Arnd Bergmann
2018-07-24 16:04 ` Wolfram Sang
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