From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 1/7] mmc: mxs-mmc: add mmc host driver for i.MX23/28 Date: Sat, 12 Feb 2011 11:07:17 +0100 Message-ID: <201102121107.17779.arnd@arndb.de> References: <1296872327-21166-1-git-send-email-shawn.guo@freescale.com> <201102120959.22707.arnd@arndb.de> <20110212172357.GB9821@S2100-06.ap.freescale.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.17.8]:51825 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750739Ab1BLKHb (ORCPT ); Sat, 12 Feb 2011 05:07:31 -0500 In-Reply-To: <20110212172357.GB9821@S2100-06.ap.freescale.net> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Shawn Guo Cc: linux-arm-kernel@lists.infradead.org, s.hauer@pengutronix.de, cjb@laptop.org, linux-mmc@vger.kernel.org, u.kleine-koenig@pengutronix.de On Saturday 12 February 2011 18:23:58 Shawn Guo wrote: > Well, we are removing inclusion of mach/dma.h from mmc driver, but > adding it to every mxs based machine code. This makes mmc driver > clean but machine code becomes not. For some dma client devices > coming later, the platform data could be saved at all, if they do not > have any. But with the approach you are suggesting, every single > client device will have to get platform data. Right, unless there is a way to encode it exlusively in the resources, which is what I was suggesting at first: If the dma engine driver knows about all the channels, you only need to pass the channel number. If you use a flattened device tree, you can avoid the need for platform data by adding the phandle of the dma engine device to a property of the mmc driver, along with the channel number inside of that device. I think that would be the cleanest approach, but some people still need to be convinced that changing drivers to use fdt data is the right direction for ARM. Arnd