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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 07/10] i3c: master: Add driver for Cadence IP
Date: Mon, 8 Oct 2018 12:36:44 +0200	[thread overview]
Message-ID: <CAK8P3a3Sck0yYzH-Ks=CvHJLgZ1VrUjHvzw2XL7C_GC515=VVg@mail.gmail.com> (raw)
In-Reply-To: <20181008122101.7b391070@bbrezillon>

On Mon, Oct 8, 2018 at 12:21 PM Boris Brezillon
<boris.brezillon@bootlin.com> wrote:
>
> On Mon, 8 Oct 2018 12:06:30 +0200
> Arnd Bergmann <arnd@arndb.de> wrote:
>
> > On Wed, Oct 3, 2018 at 3:22 PM Boris Brezillon
> > <boris.brezillon@bootlin.com> wrote:
> > >
> > > Add a driver for Cadence I3C master IP.
> > >
> > > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> > > ---
> >
> > > Changes in v7:
> > > - Fix readsl/writesl() usage
> > > - Add a depends on ARM || ARM64 || XTENSA to forbid selection of this
> > >   driver on platforms that are not implementing readsl/writesl
> >
> > Most architectures include asm-generic/io.h, which contains a generic
> > implementation of readsl(). Maybe that #ifdef could be extended here?
> > I remember discussing this with you not so long ago, which led to
> > commit 0bbf47eab469 ("ia64: use asm-generic/io.h"). Do we have
> > a list of architectures that don't include asm-generic/io.h? Maybe
> > the 'depends on' could be for the set of architectures that fail here.
>
> Well, we started patching 2 archs (ia64 and sparc) based on kbuild
> robots failure report, and then I received other reports (still from
> kbuild robots) long after the initial ones. I can't tell for sure which
> archs are not implementing those functions, hence the conservative
> approach taken here.

I think it's a fairly safe assumption that architectures which include
asm-generic/io.h will be fine here. If one of them is broken, that
can be fixed individually. Looking at the ones that don't include this
file:

grep -L asm-generic/io.h arch/*/include/asm/io*.h
arch/alpha/include/asm/io.h        # missing readsl
arch/hexagon/include/asm/io.h   # has its own readsl
arch/mips/include/asm/io.h         # missing readsl (but used from ide.h?)
arch/parisc/include/asm/io.h       # missing readsl
arch/powerpc/include/asm/io.h   # has its own readsl
arch/sh/include/asm/io.h             # has its own readsl
arch/sparc/include/asm/io.h        # has its own readsl

Based on this, I would try what happens on mips, and make it depend
on !(ALPHA || PARISC)

Another option is to just use ioread32_rep(), which should be
available everywhere and has almost the same behavior as
readsl(). The only difference is that on architectures like x86
it takes a few extra cycles to look at the address.

        Arnd

  reply	other threads:[~2018-10-08 10:37 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 [this message]
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

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