From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH] i2c: mxs: Add PIO and mixed-DMA support Date: Thu, 22 Nov 2012 12:50:37 +0100 Message-ID: <20121122115037.GA12080@pengutronix.de> References: <1353477088-9660-1-git-send-email-marex@denx.de> <201211220150.37462.marex@denx.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="a8Wt8u1KmwUX3Y2C" Return-path: Content-Disposition: inline In-Reply-To: <201211220150.37462.marex-ynQEQJNshbs@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Marek Vasut Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Fabio Estevam , Shawn Guo List-Id: linux-i2c@vger.kernel.org --a8Wt8u1KmwUX3Y2C Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 22, 2012 at 01:50:37AM +0100, Marek Vasut wrote: > Dear Marek Vasut, >=20 > > 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. > >=20 > > 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. > >=20 > > Signed-off-by: Marek Vasut > > Cc: Fabio Estevam > > Cc: Shawn Guo > > Cc: Wolfram Sang > [...] >=20 > btw. Wolfram, you might want to drop me some credit into the MX28 i2c dri= ver, I=20 > suspect most of the code in there is mine now anyway :-D It's fine if you do this yourself. --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --a8Wt8u1KmwUX3Y2C Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlCuEY0ACgkQD27XaX1/VRtr3ACeOrctJzu8IFrYH3MkhWkRjFDQ GmQAn1MiyJA7bs5/Ns3kdEtNo+sCu5/d =aomL -----END PGP SIGNATURE----- --a8Wt8u1KmwUX3Y2C--