From: Arnd Bergmann <arnd@arndb.de>
To: Boris Brezillon <boris.brezillon@bootlin.com>
Cc: Wolfram Sang <wsa@the-dreams.de>,
Linux I2C <linux-i2c@vger.kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
gregkh <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>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Sekhar Nori <nsekhar@ti.com>, Przemyslaw Gaj <pgaj@cadence.com>,
Peter Rosin <peda@axentia.se>,
mshettel@codeaurora.org, swboyd@chromium.org
Subject: Re: [PATCH v8 00/10] Add the I3C subsystem
Date: Mon, 8 Oct 2018 12:47:21 +0200 [thread overview]
Message-ID: <CAK8P3a2C+FHiPnHKEAanhD=RpqDG1VywTEGhpdBvvKQ8zmwdUA@mail.gmail.com> (raw)
In-Reply-To: <20181003132212.12619-1-boris.brezillon@bootlin.com>
On Wed, Oct 3, 2018 at 3:22 PM Boris Brezillon
<boris.brezillon@bootlin.com> wrote:
>
> Sorry for the huge delay between v7 and v8 despite the small amount of
> things I was asked to fix/rework.
>
> This patch series is adding a new subsystem to support I3C devices.
>
> This is just adding support for basic features. Extra features will
> be added afterwards.
>
> There are a few design choices that are worth mentioning because they
> impact the way I3C device drivers can interact with their devices:
>
> - all functions used to send I3C/I2C frames must be called in
> non-atomic context. Mainly done this way to ease implementation, but
> this is still open to discussion. Please let me know if you think it's
> worth considering an asynchronous model here
> - the I3C bus and I3C master controller are now tightly coupled even
> though they're still allocated separately. There's now a 1:1
> relationship between these objects, and the I3C master is no longer
> represented under the I3C bus object.
> Arnd, let me know if you had something different in mind, and I'll
> rework the implementation accordingly.
I looked at the entire series again and I'm rather happy with how
it turned out. I've commented on a tiny issue about the readsl()
that should be easy to resolve one way or another, with that
you can add my
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
There is one additional issue that we've talked about previously
and that I'd like to hear about from GregKH or maybe other
subsystem maintainers: In the current version, you have a single
'bus_type' object, and this is used to represent both a 'host' and
a 'device'. I think we concluded that this is done in other
subsystems as well, and that this is fitting here because a
host (master device) can hand over being a master to another
device (slave), which then becomes the host and sees this
one as a slave. Also a lot of the sysfs attributes are the same
because of this relationship.
It also means that you get a mix of things in sysfs:
/sys/devices/i3c/<bus>
/sys/devices/i3c/<device>
/sys/devices/i3c/<bus>/<device>
which is a bit like what we have on USB where we can have hub
devices that are again parents of other USB devices, but I don't
think we can have i3c hubs or multiplexers in the same way, so
it's only a single level.
I'm ok with this model after our previous discussion and couldn't
come up with a better one. If anyone else still sees it as
problematic and has a better idea, please let us know now.
Arnd
next prev parent reply other threads:[~2018-10-08 10:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 13:22 [PATCH v8 00/10] Add the I3C subsystem Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 01/10] i3c: Add core I3C infrastructure Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 02/10] docs: driver-api: Add I3C documentation Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 03/10] i3c: Add sysfs ABI spec Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 04/10] dt-bindings: i3c: Document core bindings Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 05/10] dt-bindings: i3c: Add macros to help fill I3C/I2C device's reg property Boris Brezillon
2018-10-03 18:37 ` Joe Perches
2018-10-03 18:45 ` Geert Uytterhoeven
2018-10-03 19:02 ` Joe Perches
2018-10-03 18:59 ` Boris Brezillon
2018-10-03 19:06 ` Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 06/10] MAINTAINERS: Add myself as the I3C subsystem maintainer Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 07/10] i3c: master: Add driver for Cadence IP Boris Brezillon
2018-10-08 10:06 ` Arnd Bergmann
2018-10-08 10:21 ` Boris Brezillon
2018-10-08 10:36 ` Arnd Bergmann
2018-10-08 12:05 ` Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 08/10] dt-bindings: i3c: Document Cadence I3C master bindings Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 09/10] gpio: Add a driver for Cadence I3C GPIO expander Boris Brezillon
2018-10-03 13:22 ` [PATCH v8 10/10] dt-bindings: gpio: Add bindings for Cadence I3C gpio expander Boris Brezillon
2018-10-04 8:35 ` Linus Walleij
2018-10-08 10:47 ` Arnd Bergmann [this message]
2018-10-17 13:18 ` [PATCH v8 00/10] Add the I3C subsystem Boris Brezillon
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