Re: [PATCH v3 00/17] Cross-architecture definitions of relaxed MMIO accessors

From: Arnd Bergmann
Date: Thu Sep 25 2014 - 06:43:14 EST

On Wednesday 24 September 2014 18:17:19 Will Deacon wrote:
> This is version three of the series I've originally posted here:
> v1:
> v2:
> This is basically just a rebase on top of 3.17-rc6, minus the alpha patch
> (which was merged into mainline).
> I looked at reworking the non-relaxed accessors to imply mmiowb, but it
> quickly got messy as some architectures (e.g. mips) deliberately keep
> mmiowb and readX/writeX separate whilst others (e.g. powerpc) don't trust
> drivers to get mmiowb correct, so add barriers to both. Given that
> arm/arm64/x86 don't care about mmiowb, I've left that as an exercise for
> an architecture that does care.
> In order to get this lot merged, we probably want to merge the asm-generic
> patch (1/17) first, so Acks would be much appreciated on the architecture
> bits.
> As before, I've included the original cover letter below, as that describes
> what I'm trying to do in more detail.

I'm definitely happy to merge that first patch in the asm-generic tree, or
have it go through some other tree along with architecture specific patches.
Anything that helps get these functions across all architectures really.

I don't think there is any controversy about whether or not we should
have the functions, or what the default should be on architectures that
don't provide their own, so I wonder why we can't just add the conditional
definitions to linux/io.h and remove the trivial definitions from
architectures afterwards.

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