From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH V2] i2c: mxs: Add PIO and mixed-DMA support Date: Thu, 24 Jan 2013 15:17:15 +0100 Message-ID: <20130124141715.GJ12933@pengutronix.de> References: <1359032181-10601-1-git-send-email-marex@denx.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Tu8ztk+XgTAiG9Id" Return-path: Content-Disposition: inline In-Reply-To: <1359032181-10601-1-git-send-email-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 --Tu8ztk+XgTAiG9Id Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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. >=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 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! --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --Tu8ztk+XgTAiG9Id Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlEBQmsACgkQD27XaX1/VRsN1QCeMgPyzGnYG7gUlBC6UVxckjuE Ae8An0ffjQIe9CaUdNsu4Brd3UJyXkEn =VxSo -----END PGP SIGNATURE----- --Tu8ztk+XgTAiG9Id--