linux-kernel - Re: [PATCH] 6fire: Convert byte_rev

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Message-ID: <1414551974.10912.16.camel@perches.com>
Date:	Tue, 28 Oct 2014 20:06:14 -0700
From:	Joe Perches <joe@...ches.com>
To:	"Wang, Yalin" <Yalin.Wang@...ymobile.com>
Cc:	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	Russell King <linux@....linux.org.uk>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Will Deacon <Will.Deacon@....com>,
	Akinobu Mita <akinobu.mita@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	alsa-devel <alsa-devel@...a-project.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] 6fire: Convert byte_rev_table uses to bitrev8

On Wed, 2014-10-29 at 10:42 +0800, Wang, Yalin wrote:
> > Use the inline function instead of directly indexing the array.
> > This allows some architectures with hardware instructions for bit reversals
> > to eliminate the array.
[]
> > On Sun, 2014-10-26 at 23:46 -0700, Joe Perches wrote:
> > > On Mon, 2014-10-27 at 14:37 +0800, Wang, Yalin wrote:
> > > > this change add CONFIG_HAVE_ARCH_BITREVERSE config option, so that
> > > > we can use arm/arm64 rbit instruction to do bitrev operation by
> > > > hardware.
[]
> I think the most safe way is change byte_rev_table[] to be satic,
> So that no driver can access it directly,
> The build error can remind the developer if they use byte_rev_table[]
> Directly .

You can do that with your later patch, but the
existing uses _must_ be converted first so you
don't break the build.



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