linux-kernel - Re: [PATCH v2 1/3] asm-generic/io.h: Implement generic {read,write}s*()

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Message-ID: <53C05E4A.2030708@codeaurora.org>
Date:	Fri, 11 Jul 2014 14:59:38 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Ben Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH v2 1/3] asm-generic/io.h: Implement generic {read,write}s*()

On 07/11/14 08:31, Thierry Reding wrote:
> From: Thierry Reding <treding@...dia.com>
>
> This patch implements generic versions of readsb(), readsw(), readsl(),
> readsq(), writesb(), writesw(), writesl() and writesq(). Variants of
> these string functions for I/O accesses (ins*() and outs*() as well as
> ioread*_rep() and iowrite*_rep()) are now implemented in terms of the
> new functions.
>
> While at it, also make sure that any of the functions provided as
> fallback for architectures that don't override them can't be overridden
> subsequently.
>
> This is compile- and runtime-tested on 32-bit and 64-bit ARM and compile
> tested on Microblaze, s390, SPARC and Xtensa. For ARC, Blackfin, Metag,
> OpenRISC, Score and Unicore32 which also use asm-generic/io.h I couldn't
> find or build a cross-compiler that would run on my system. But by code
> inspection they shouldn't break with this patch.
>
> Signed-off-by: Thierry Reding <treding@...dia.com>

There isn't any mention of why we're doing this in the commit text. It
looks like patch 2 and 3 sort of mention why.

I also wonder if it could be explained how this about turn is desired,
given that patch b2656a138ab7 (asm-generic: io: remove {read,write}
string functions, 2012-10-17) did the complete opposite. Can you please
explain?

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