From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 2/2] drivers/gpio: Port gpio driver to layerscape platform
Date: Wed, 04 Nov 2015 11:09:58 +0100
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References: <1446619704-27669-1-git-send-email-Gang.Liu@freescale.com> <4040829.fHtCUjX87j@wuerfel> <1446628658.12676.14.camel@freescale.com>
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Cc: Scott Wood <scottwood@freescale.com>, devicetree@vger.kernel.org, R58472@freescale.com, b07421@freescale.com, Shaveta Leekha <shaveta@freescale.com>, linus.walleij@linaro.org, bhupesh.sharma@freescale.com, Liu Gang <Gang.Liu@freescale.com>, robh+dt@kernel.org, linux-gpio@vger.kernel.org, shawnguo@kernel.org
List-Id: devicetree@vger.kernel.org

On Wednesday 04 November 2015 03:17:38 Scott Wood wrote:
> > I guess this is fixed per architecture, so you could also do this as
> > 
> > static inline void gpio_out32(u32 val, void __iomem *addr)
> > {
> >       if (IS_ENABLED(CONFIG_ARM))
> >               iowrite32(val, addr);
> >       else if (IS_ENABLED(CONFIG_PPC))
> >               iowrite32be(val, addr);
> >       else
> >               BUG();
> > }
> 
> Unfortunately that guess is wrong.  Some of our ARM chips have big-endian I/O 
> and some have little-endian I/O.

Ok, I see. In that case, using run-time detection everywhere is
probably best.

	Arnd