From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        Lior Amsalem <alior@marvell.com>, Andrew Lunn <andrew@lunn.ch>,
        Jason Cooper <jason@lakedaemon.net>, Vinod Koul <vinod.koul@intel.com>,
        dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Thomas Petazzoni <thomas@free-electrons.com>,
        linux-crypto@vger.kernel.org,
        Gregory Clement <gregory.clement@free-electrons.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Maxime Ripard <maxime.ripard@free-electrons.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH 2/8] dmaengine: mv_xor: add support for a38x command in descriptor mode
Date: Tue, 12 May 2015 18:03:34 +0200
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On Tuesday 12 May 2015 17:54:31 Thomas Petazzoni wrote:
> Dear Arnd Bergmann,
> 
> On Tue, 12 May 2015 17:49:08 +0200, Arnd Bergmann wrote:
> 
> > Using 
> > 
> >       if (IS_ENABLED(__BIG_ENDIAN))
> > 
> > here would make it more readable by avoiding the #if. Alternatively,
> > you could leave the XOR_DESCRIPTOR_SWAP flag disabled and just swap
> > the descriptors manually like a lot of other drivers do. You have
> > to swap the mmio accesses anywya.
> 
> Agreed on IS_ENABLED(). However, I don't understand the comment about
> the need to swap mmio accesses? We're using readl_relaxed() /
> writel_relaxed(), and they do the swapping already. Am I missing
> something?
> 

Sorry for being unclear. This was exactly my point: readl_relaxed()
has to do swaps internally, and you can also do swaps when accessing
the descriptor in memory.

	Arnd
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