From: David Brownell <david-b@pacbell.net>
To: stephen@streetfiresound.com
Cc: Manish Jaggi <manish.jaggi@gmail.com>,
spi-devel-general@lists.sourceforge.net,
Luke Yang <luke.adi@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [spi-devel-general] [Patch] Add spi full duplex mode transfer support
Date: Wed, 30 Aug 2006 09:26:31 -0700 [thread overview]
Message-ID: <200608300926.32532.david-b@pacbell.net> (raw)
In-Reply-To: <1156953418.6555.13.camel@localhost>
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
prev parent reply other threads:[~2006-08-30 16:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-30 4:40 [Patch] Add spi full duplex mode transfer support Luke Yang
2006-08-30 4:52 ` [spi-devel-general] " David Brownell
[not found] ` <2e2add590608300337h3e7e806bs69b63b24d73a104c@mail.gmail.com>
2006-08-30 15:35 ` David Brownell
2006-08-30 15:56 ` Stephen Street
2006-08-30 16:26 ` David Brownell [this message]
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