From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753816Ab1JBSBi (ORCPT ); Sun, 2 Oct 2011 14:01:38 -0400 Received: from moutng.kundenserver.de ([212.227.126.186]:53967 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751567Ab1JBSBc (ORCPT ); Sun, 2 Oct 2011 14:01:32 -0400 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: Russell King - ARM Linux , Tony Lindgren , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, Felipe Balbi Subject: Re: [PATCH 15/30] usb/musb: use a Kconfig choice to pick the right DMA method Date: Sun, 02 Oct 2011 20:00:31 +0200 Message-ID: <1757336.Qk72n3s00p@wuerfel> User-Agent: KMail/4.7.1 (Linux/3.0.0-rc1nosema+; KDE/4.7.1; x86_64; ; ) In-Reply-To: <20111002161447.GC12323@n2100.arm.linux.org.uk> References: <1317566760-25681-1-git-send-email-arnd@arndb.de> <1317566760-25681-16-git-send-email-arnd@arndb.de> <20111002161447.GC12323@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:cRlO3zO2TYxvJZlssNr6TdU9ZmfvzLH2yaOd6Iarg+Z Nw03Y9ivjI3azSM+5oBhI5a8K2sRaY9WA7ebrz1se9meG6xGrD 14aJUqsguwP2DztkERTZF5076GZT0UCCDsmXiXzY8cbGpNIcv3 lBZgeFjMO7Tf7435vilb5L7u6cXuy780FBnOH+a+UUmgdUQB9e PR8EEWXB3Ml9SU5UKKR35R+F683yPpe0Ea7fTzd/2Ga3MARg2z fNyMNfUUwgb1qao2D9rIyuvU9UvNJCQ4sM1XLLlsEFkpof8bgV 0OVRJJqZ7ZEZSdd0qXotl3TikIkcnbH6tijvFwKqBqyMoz8BGf Hdl/EuwnklbNaxAVpsTw= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 02 October 2011 17:14:47 Russell King - ARM Linux wrote: > On Sun, Oct 02, 2011 at 04:45:45PM +0200, Arnd Bergmann wrote: > > The logic to allow only one DMA driver in MUSB is currently > > flawed, because it also allows picking no DMA driver at all > > and also not selecting PIO mode. > > > > Using a choice statement makes this foolproof for now and > > also simplifies the Makefile. > > > > Unfortunately, we will have to revisit this when we start > > supporting multiple ARM platforms in a single kernel binary, > > because at that point we will actually need to select > > multiple DMA drivers and pick the right one at run-time. > > I thought there was some work going on to convert this to use the > dmaengine stuff? That would certainly be the best solution here, I wasn't aware that it has already been discussed. Unfortunately, even with the dma parts out of the way there is a lot that needs to be done to make musb, ehci or ohci really cross-platform. Right now, you can only have one platform driver glue for each of those drivers, and they should eventually be converted to a large library module for the core, with independent platform driver front-end, similar to the recent conversion of the sdhci driver by Shawn Guo, and the way that a lot of the other common drivers work. Arnd