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Date: Wed, 11 Nov 2009 15:54:39 +0100
From: =?ISO-8859-1?Q?Richard_R=F6jfors?= <richard.rojfors@mocean-labs.com>
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To: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/4] xilinx_spi: Switch to iomem functions and support
	little endian.
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Cc: spi-devel-general@lists.sourceforge.net,
	Andrew Morton <akpm@linux-foundation.org>, dbrownell@users.sourceforge.net,
	John Linn <John.Linn@xilinx.com>, linuxppc-dev@ozlabs.org
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Josh Boyer wrote:
> On Wed, Nov 11, 2009 at 03:38:34PM +0100, Richard Röjfors wrote:
>> This patch changes the out_(be)(8|16|32) and in_(be)(8|16|32) calls to iowrite(8|16|32)
>> and ioread(8|16|32). This to be able to build on platforms not supporting the in/out calls
>> for instance x86.
>>
>> Support is also added for little endian writes. In some systems the registers should be
>> accessed little endian rather than big endian.
> 
> I wonder if you should make the endianness a config option.  Right now you
> have a conditional check for every read and write.  Does that impact
> performance at all?

It won't affect the performance noticeable.

In our case we need the possibility to run both endians using the same xilinx_spi module.

--Richard