Re: [PATCH V2] i2c: mxs: Add PIO and mixed-DMA support

[Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

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On Thu, Jan 24, 2013 at 01:56:21PM +0100, Marek Vasut wrote:
> Add support for the PIO mode and mixed PIO/DMA mode support. The mixed
> PIO/DMA is the default mode of operation. This shall leverage overhead
> that the driver creates due to setting up DMA descriptors even for very
> short transfers.
> 
> The current boundary between PIO/DMA 8 bytes, transfers shorter than 8
> bytes are transfered by PIO, longer transfers use DMA. The performance
> of write transfers remains unchanged, while there is a minor improvement
> of read performance. Reading 16KB EEPROM with DMA-only operations gives
> a read speed of 39.5KB/s, while with then new mixed-mode the speed is
> blazing 40.6KB/s.
> 
> Signed-off-by: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
> Cc: Fabio Estevam <fabio.estevam-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> Cc: Shawn Guo <shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Cc: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

OK, the polling can be argued. I shortened the comment about the
threshold a little, since bandwidth measurements depend on a lot of
other things and it is not really needed there.

Applied to -next, thanks!

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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