Messages in this thread | | | From | David Brownell <> | 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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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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