From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Subject: Re: [PATCH V2] i2c: mxs: Add PIO and mixed-DMA support Date: Thu, 24 Jan 2013 15:18:41 +0100 Message-ID: <201301241518.41593.marex@denx.de> References: <1359032181-10601-1-git-send-email-marex@denx.de> <20130124141715.GJ12933@pengutronix.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130124141715.GJ12933-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Fabio Estevam , Shawn Guo List-Id: linux-i2c@vger.kernel.org Dear Wolfram Sang, > 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 > > Cc: Fabio Estevam > > Cc: Shawn Guo > > Cc: Wolfram Sang > > 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! Thank you very much! And good luck with the stuff up ahead ;-) Best regards, Marek Vasut