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From: David Brownell <david-b@pacbell.net>
To: stephen@streetfiresound.com
Subject: Re: [spi-devel-general] [Patch] Add spi full duplex mode transfer support
Date: Wed, 30 Aug 2006 09:26:31 -0700
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Cc: Manish Jaggi <manish.jaggi@gmail.com>,
       spi-devel-general@lists.sourceforge.net, Luke Yang <luke.adi@gmail.com>,
       linux-kernel@vger.kernel.org
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On Wednesday 30 August 2006 8:56 am, Stephen Street wrote:

> My experiance has shown the most stack allocated transfer buffers are
> not 8 byte aligned and thus use PIO mode.

Of course, providing a transfer buffer on the stack is nonportable;
it's not DMA-safe (especially on systems with dma-incoherent caches!),
while transfer buffers are required to be DMA-safe so that controller
buffers can choose to use DMA for _all_ transfers if they want.

- Dave


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