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From: Boris Brezillon <boris.brezillon@bootlin.com>
To: gregkh <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>, 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>,
	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: Wed, 17 Oct 2018 15:18:29 +0200	[thread overview]
Message-ID: <20181017151829.470930a7@bbrezillon> (raw)
In-Reply-To: <CAK8P3a2C+FHiPnHKEAanhD=RpqDG1VywTEGhpdBvvKQ8zmwdUA@mail.gmail.com>

Hi Greg,

On Mon, 8 Oct 2018 12:47:21 +0200
Arnd Bergmann <arnd@arndb.de> wrote:

> 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.

I know you're quite busy with the 4.19 release, but if you find a bit
of time, that'd be great to have your feedback on this.

Thanks,

Boris

      reply	other threads:[~2018-10-17 13:18 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 ` [PATCH v8 00/10] Add the I3C subsystem Arnd Bergmann
2018-10-17 13:18   ` Boris Brezillon [this message]

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