Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754397AbXIIVsD (ORCPT ); Sun, 9 Sep 2007 17:48:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750998AbXIIVry (ORCPT ); Sun, 9 Sep 2007 17:47:54 -0400 Received: from az33egw01.freescale.net ([192.88.158.102]:56474 "EHLO az33egw01.freescale.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750700AbXIIVry (ORCPT ); Sun, 9 Sep 2007 17:47:54 -0400 Message-ID: <46E46A3F.2050708@freescale.com> Date: Sun, 09 Sep 2007 16:48:47 -0500 From: Timur Tabi Organization: Freescale User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.8.1.6) Gecko/20070802 SeaMonkey/1.1.4 MIME-Version: 1.0 To: Dan Williams CC: Zhang Wei , shannon.nelson@intel.com, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, paulus@samba.org Subject: Re: [PATCH 5/5] Add DMA engine driver for Freescale MPC85xx processors. References: <11891624582950-git-send-email-wei.zhang@freescale.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1356 Lines: 28 Dan Williams wrote: > This routine implies that there is a piece of code somewhere that > wants to select which channels it can use. A similar effect can be > achieved by registering a dma_client with the dmaengine interface > ('dma_async_client_register'). Then when the client code makes a call > to 'dma_async_client_chan_request' it receives a 'dma_event_callback' > for each channel in the system. It will also be asynchronously > notified of channels entering and leaving the system. The goal is to > share a common infrastructure for channel management. Are you familiar with the "flat device tree" used for PowerPC systems? The "piece of code somewhere" is the device tree subsystem that parses the device tree, which is compiled from the .dts files in arch/powerpc/boot/dts. The FDT is how PowerPC systems specify hardware configuration. In the case of 85xx, the FDT contains entries for each DMA device (typically 2), and the entries contain sub-entries for each DMA channel as well as the address of the register sets for each channel. -- Timur Tabi Linux Kernel Developer @ Freescale - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/