From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753077Ab2DCJHl (ORCPT ); Tue, 3 Apr 2012 05:07:41 -0400 Received: from moutng.kundenserver.de ([212.227.126.186]:62592 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751572Ab2DCJHj (ORCPT ); Tue, 3 Apr 2012 05:07:39 -0400 From: Arnd Bergmann To: Kyungmin Park Subject: Re: Linux 3.4-rc1 Date: Tue, 3 Apr 2012 09:07:28 +0000 User-Agent: KMail/1.12.2 (Linux/3.3.0-rc1; KDE/4.3.2; x86_64; ; ) Cc: Linus Torvalds , Linux Kernel Mailing List , vdumpa@nvidia.com, hdoyu@nvidia.com, konrad.wilk@oracle.com References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201204030907.29306.arnd@arndb.de> X-Provags-ID: V02:K0:mxQwxbAk7YwcxurVc5+fWpG22iIjFDtKXj4z4LV1bd5 NzfZB/KeMHfHrTT2HtaWsFtRhPXpNh7Zo+E3++L4BvjgEJIS1q ZoRbMLRHjRG0n7vTlFHRRS3UfWzNhpYuucN0LU4ygHYmcn+vyl v4+YPO103n8yKiSOvqU4Dhxo8rHdOaVM1H2QU88VRrfg6NI3IV FRMfgGSFeObGu/DzrXa4bD+OzYf1pT9PPpCkiy+QSm7oNDfxPB +ifwPN4L32ph9RCeDXcTEb/U8yJ0FJjgPUvw7NkYt8WD+tJfi0 LcOSGOV0DUCQlLcA3UrMuZz84ylqcnF2CwV++7qXoFEZU2Gdwz lsJChnsktfW+c5+FHxAc= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 03 April 2012, Kyungmin Park wrote: > > > > - DMA-mapping framework. The tree now has a few more acks from > > people, and it's largely in the same situation as HSI is: I'll > > probably pull, but I really wanted the users who are impacted to > > actually talk to me about it. > > > Hi, > > Now Marek and Nvidia persons are used it for DMA mapping based IOMMU. > > Are there other person who help to merge it? > (+CC related persons). I can give a little more background information. We used to have separate implementations of dma_map_ops for each architecture that had the need to abstract dma_alloc_coherent and dma_map_* across both IOMMU and linear (virt_to_bus style) mappings and/or swiotlb. Those dma_map_ops imlpementations were already merged before the start of the git history and subsequently got used on powerpc, ia64, x86_64, sparc, alpha, mips, unicore32 and hexagon, roughly in that order. We are seeing lots of IOMMUs come up on ARM now, but unfortunately the existing dma_map_ops do not cover the need on ARM to have two different kind of coherent memory (write-combine and not write-combine) that we have traditionally abstracted using the dma_alloc_coherent and dma_alloc_writecombine functions on both arm and avr32. In order to support IOMMUs on ARM using the same API as everyone else, I've asked Marek to use dma_map_ops on ARM, which requires slightly extending the include/linux/dma-mapping.h interfaces so they cover this variation. The actually interesting work to implement a better abstraction for IOMMUs, building the dma-mapping.h API on top of the iommu.h API in an architecture independent way has also been implemented but requires these changes as a prerequisite. Arnd