From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751669Ab1LTMpH (ORCPT ); Tue, 20 Dec 2011 07:45:07 -0500 Received: from va3ehsobe006.messaging.microsoft.com ([216.32.180.16]:32536 "EHLO VA3EHSOBE007.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750830Ab1LTMpA (ORCPT ); Tue, 20 Dec 2011 07:45:00 -0500 X-SpamScore: -12 X-BigFish: VS-12(zz936eK1432N98dKzz1202hzzz2dh2a8h668h839h944h) X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI Date: Tue, 20 Dec 2011 20:54:02 +0800 From: Shawn Guo To: Vinod Koul CC: Shawn Guo , Chris Ball , Artem Bityutskiy , , Huang Shijie , , , Subject: Re: [PATCH 0/4] Fix the left DMA_NONE from dma_transfer_direction migration Message-ID: <20111220125401.GA5129@S2101-09.ap.freescale.net> References: <1323791286-29574-1-git-send-email-shawn.guo@linaro.org> <1324373044.1641.10096.camel@vkoul-udesk3> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1324373044.1641.10096.camel@vkoul-udesk3> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 20, 2011 at 02:54:04PM +0530, Vinod Koul wrote: > On Tue, 2011-12-13 at 23:48 +0800, Shawn Guo wrote: > > I have been working on -rc recently, and have not noticed the failure > > until I ran next tree today. The mxs-mmc driver is broken on next > > tree because the DMA_NONE was left over from the dma_transfer_direction > > migration for mxs-dma and its client drivers. > > > For DMA transfer, the NONE direction makes no sense? > > In your conetext, what are you trying to achieve? > The mxs-dma controller has a feature to program peripheral registers with given values (mxs-dma PIO mode). This is designed to pipeline the operations. For example, we can put mxs-mmc controller register values into scatter list as one element together with actual data. Triggering the mxs-dma, the dma will program the values into mxs-mmc controller register to set up and enable mxs-mmc, and then dma continue transfer data from/to mxs-mmc. All these get done in one dmaengine_submit(). And DMA_NONE was used to let mxs-dma know this is a PIO operation. -- Regards, Shawn