From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932459Ab2ITWxW (ORCPT ); Thu, 20 Sep 2012 18:53:22 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:40191 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932159Ab2ITWxS (ORCPT ); Thu, 20 Sep 2012 18:53:18 -0400 Date: Thu, 20 Sep 2012 18:53:15 -0400 (EDT) Message-Id: <20120920.185315.576326460331670020.davem@davemloft.net> To: benh@kernel.crashing.org Cc: sfr@canb.auug.org.au, paulus@samba.org, linuxppc-dev@lists.ozlabs.org, mika.westerberg@linux.intel.com, netdev@vger.kernel.org, linux-next@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: linux-next: build failure after merge of the final tree (net-next tree related) From: David Miller In-Reply-To: <1348179764.1132.35.camel@pasglop> References: <20120920.164558.2281417114805373564.davem@davemloft.net> <20120921081531.67db8a7d0ac1b35426b22c45@canb.auug.org.au> <1348179764.1132.35.camel@pasglop> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Benjamin Herrenschmidt Date: Fri, 21 Sep 2012 08:22:44 +1000 > Hrm, that's ancient gunk, I'll have to dig. We potentially can support > ISA devices DMA'ing from an ISA bridge... but via the iommu, which means > isa_virt_to_bus is a non-starter. > > But then, do we really care ? IE. Is there single device that actually > requires ISA_DMA_API and that is expected to work on any currently > supported powerpc hw ? :-) > > We don't even support PReP anymore, so that leaves us with what ? ISA_DMA_API implies a fixed window of addresses which are <= 32-bits on the bus, which is a hardware requirement of these devices. isa_virt_to_bus() goes to that physical address, and the expection is that you use GFP_DMA and thus the physical addresses fit inside of an unsigned int. isa_virt_to_bus() basically amounts to a virt-->phys plus a cast. > Anybody has an objection to turning ISA_DMA_API off ? Then you can remove all of the DMA api stuff in powerpc's asm/dma.h but some of it looks like it might be in use.