From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anatolij Gustschin Subject: Re: [PATCH 4/5] mmc: mxcmmc: enable DMA support on mpc512x Date: Thu, 14 Mar 2013 22:18:16 +0100 Message-ID: <20130314221816.1e4c93c1@crub> References: <1363279254-22351-1-git-send-email-agust@denx.de> <1363279254-22351-6-git-send-email-agust@denx.de> <20130314201139.GS1906@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130314201139.GS1906@pengutronix.de> Sender: linux-mmc-owner@vger.kernel.org To: Sascha Hauer Cc: linux-mmc@vger.kernel.org, Chris Ball , Markus Pargmann , devicetree-discuss@lists.ozlabs.org List-Id: devicetree@vger.kernel.org On Thu, 14 Mar 2013 21:11:39 +0100 Sascha Hauer wrote: > On Thu, Mar 14, 2013 at 05:40:53PM +0100, Anatolij Gustschin wrote: > > Add SDHC DMA channel description to the mpc512x device > > tree to enable slave channel requesting in the mxcmmc > > driver. > > > > mpc512x DMA engine doesn't support endianness conversion > > when reading/writing data from peripheral's FIFO, so we > > have to swap data buffers before each DMA write and after > > each DMA read transfer manually. > > > > Since chained SDHC DMA transfers are not supported on > > mpc512x, limit 'max_segs' tunable parameter to one and > > initialise it to 64 only when running on i.MX platforms. > > They are also not supported on the older i.MX platforms. Shouldn't this > be handled in the DMA driver? This could be handled in the DMA driver, but up to now nobody cared to extend the DMA driver so. Anatolij