From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754083AbXJCGSY (ORCPT ); Wed, 3 Oct 2007 02:18:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751479AbXJCGSR (ORCPT ); Wed, 3 Oct 2007 02:18:17 -0400 Received: from smtp.ocgnet.org ([64.20.243.3]:36144 "EHLO smtp.ocgnet.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751162AbXJCGSQ (ORCPT ); Wed, 3 Oct 2007 02:18:16 -0400 Date: Wed, 3 Oct 2007 15:18:05 +0900 From: Paul Mundt To: Adrian McMenamin Cc: linux-sh , LKML Subject: Re: [PATCH] Fix SH DMAC code to handle PVR2 cascade Message-ID: <20071003061805.GA8851@linux-sh.org> Mail-Followup-To: Paul Mundt , Adrian McMenamin , linux-sh , LKML References: <1191359367.17654.24.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1191359367.17654.24.camel@localhost.localdomain> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 02, 2007 at 10:09:27PM +0100, Adrian McMenamin wrote: > Fix SH DMAC code to correctly handle PVR2 cascade DMA. > > This updates http://lkml.org/lkml/2007/10/2/276 > > (I decided it was better to have the true size of the transfer put in > via the API and refactor this here. And calc_xmit_shift(chan) should > return 5 but only returns 3 so I've not used it here) > It would be helpful to know why calc_xmit_shift() is broken here rather than just coding around it, as this will have implications for the other DMA channels on SH7091/SH7750. Now that you've completely bypassed the rest of the SH-DMAC ->xfer_dma() op, it's clear that the existing infrastructure needs a bit of rework for dealing with the cascaded DMACs (especially for single-address mode only, unidirectionally). It would be nice to get the mach-specific kludges for cascade out of dma-sh entirely. This can certainly be fixed for 2.6.24, though a larger overhaul is 2.6.25 material at this point.