linux-kernel - Re: [PATCH 2/2] asm-generic: io: don't perform swab during {in,out} string functions

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Message-Id: <201204271326.29088.vapier@gentoo.org>
Date:	Fri, 27 Apr 2012 13:26:26 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	Will Deacon <will.deacon@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"uclinux-dist-devel@...ckfin.uclinux.org" 
	<uclinux-dist-devel@...ckfin.uclinux.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 2/2] asm-generic: io: don't perform swab during {in,out} string functions

On Friday 27 April 2012 12:59:19 Will Deacon wrote:
> On Fri, Apr 27, 2012 at 05:18:58PM +0100, Mike Frysinger wrote:
> > On Friday 27 April 2012 06:42:56 Will Deacon wrote:
> > > The {in,out}s{b,w,l} functions are designed to operate on a stream of
> > > bytes and therefore should not perform any byte-swapping, regardless of
> > > the CPU byte order.
> > 
> > says who ?  where's the agreed upon documentation for this ?
> 
> This specific case is actually documented in Linux Device Drivers

if it isn't in the tree (either Documentation/ or in asm-generic/io.h itself), 
i don't think it's acceptable to refer to it as guiding documentation

> appreciate that it's not especially clear. I had some offline discussion
> with Arnd where we agreed on this -- it also means that asm-generic/io.h
> matches what is done by bi-endian architectures providing their own
> accessors.

please add start adding comments above these functions that clearly spell out 
the expectations and behavior
-mike

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