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Date: Fri, 18 Oct 2013 00:42:30 +0100
From: Mark Brown <broonie@kernel.org>
To: "Gupta, Pekon" <pekon@ti.com>
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Subject: Re: [PATCH 1/3] spi/qspi: Add memory mapped read support.
Cc: Peter Korsgaard <peter@korsgaard.com>,
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On Thu, Oct 17, 2013 at 01:03:26PM +0000, Gupta, Pekon wrote:

> mtd_read() {
> 	if (flash->mmap_mode)
> 		if (dma_available)
> 			read_via_dma(destination, source, length);
> 		else
> 			memcpy(destination, source, length);
> 	else
> 		/* use spi frame-work by default */
> }

> Are you looking for comparison between  read_via_dma() v/s memcpy() ?

No, I'm looking for a comparison of normal SPI mode (which I'd have
expected to DMA) and the memcpy() mode.

> If yes, then unfortunately we are bit constrained because our controller
> does not support DMA. So, we have to depend on CPU based memcpy()
> only. However, use of DMA can be added as an independent patch on
> top of this CASE-2 patch.

However if the controller can't DMA at all then that's not going to be
possible...  am I understanding you correctly that normal SPI can't DMA?

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