From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: possible MXS-i2c bug Date: Fri, 27 Apr 2012 16:59:36 +0200 Message-ID: <20120427145936.GD16504@pengutronix.de> References: <201204261326.29388.marex@denx.de> <20120426114201.GC3548@pengutronix.de> <201204270110.21377.marex@denx.de> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="GyRA7555PLgSTuth" Return-path: Content-Disposition: inline In-Reply-To: <201204270110.21377.marex-ynQEQJNshbs@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Marek Vasut Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Fabio Estevam , Shawn Guo , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org --GyRA7555PLgSTuth Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, > I've been thinking about the DMA approach. The problem I found out is tha= t we=20 > need to transfer all messages we're given at time in one DMA chain ... at= least=20 > that's how I understand it from the FSL manual (see Fig. 27-10 in the mx2= 8=20 > manual). I can't follow you: mxs_i2c_xfer() gets a list of messages, yet they are iterated over in mxs_i2c_xfer_msg(). A single I2C message is unscattered and can't be bigger than 64KB, so that should be doable? Am I missing something by already being in weekend-mode? :) --=20 Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | --GyRA7555PLgSTuth Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAk+atFgACgkQD27XaX1/VRvB+QCeOxd8Of/CMgfHUw2TG7MuElmQ AeAAn1tFOY2aHey+wGNwF/vfpl7TnXis =MdPE -----END PGP SIGNATURE----- --GyRA7555PLgSTuth-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: w.sang@pengutronix.de (Wolfram Sang) Date: Fri, 27 Apr 2012 16:59:36 +0200 Subject: possible MXS-i2c bug In-Reply-To: <201204270110.21377.marex@denx.de> References: <201204261326.29388.marex@denx.de> <20120426114201.GC3548@pengutronix.de> <201204270110.21377.marex@denx.de> Message-ID: <20120427145936.GD16504@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, > I've been thinking about the DMA approach. The problem I found out is that we > need to transfer all messages we're given at time in one DMA chain ... at least > that's how I understand it from the FSL manual (see Fig. 27-10 in the mx28 > manual). I can't follow you: mxs_i2c_xfer() gets a list of messages, yet they are iterated over in mxs_i2c_xfer_msg(). A single I2C message is unscattered and can't be bigger than 64KB, so that should be doable? Am I missing something by already being in weekend-mode? :) -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: