Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751712AbeACHtm (ORCPT + 1 other); Wed, 3 Jan 2018 02:49:42 -0500 Received: from mail-qk0-f196.google.com ([209.85.220.196]:34935 "EHLO mail-qk0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167AbeACHth (ORCPT ); Wed, 3 Jan 2018 02:49:37 -0500 X-Google-Smtp-Source: ACJfBosjKbQ3lZy+Ip0KcMk6EGDf7VZMtuMoPU4vodAfZ0xh/mp9uKJMqwr3QljTEFf2n85CWmBPVY3pXtHAmk/D7nI= MIME-Version: 1.0 In-Reply-To: <87h8s3cvel.fsf@concordia.ellerman.id.au> References: <20171229081911.2802-1-hch@lst.de> <20171229081911.2802-17-hch@lst.de> <878tdgtwzp.fsf@concordia.ellerman.id.au> <87h8s3cvel.fsf@concordia.ellerman.id.au> From: Geert Uytterhoeven Date: Wed, 3 Jan 2018 08:49:35 +0100 X-Google-Sender-Auth: oqSUvd2ZdU5LGG2QV3eD-O97YFc Message-ID: Subject: Re: [PATCH 16/67] powerpc: rename dma_direct_ to dma_nommu_ To: Michael Ellerman Cc: Christoph Hellwig , iommu@lists.linux-foundation.org, Linux MIPS Mailing List , linux-ia64@vger.kernel.org, Linux-sh list , sparclinux , Guan Xuetao , Linux-Arch , linux-s390 , linux-c6x-dev@linux-c6x.org, "open list:QUALCOMM HEXAGON..." , "the arch/x86 maintainers" , arcml , adi-buildroot-devel@lists.sourceforge.net, linux-m68k , patches@groups.riscv.org, "open list:METAG ARCHITECTURE" , linux-arm-kernel@lists.infradead.org, Michal Simek , Parisc List , Cris , Linux Kernel Mailing List , alpha , linuxppc-dev@lists.ozlabs.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Hi Michael, On Wed, Jan 3, 2018 at 7:24 AM, Michael Ellerman wrote: > Geert Uytterhoeven writes: > >> On Tue, Jan 2, 2018 at 10:45 AM, Michael Ellerman wrote: >>> Christoph Hellwig writes: >>> >>>> We want to use the dma_direct_ namespace for a generic implementation, >>>> so rename powerpc to the second best choice: dma_nommu_. >>> >>> I'm not a fan of "nommu". Some of the users of direct ops *are* using an >>> IOMMU, they're just setting up a 1:1 mapping once at init time, rather >>> than mapping dynamically. >>> >>> Though I don't have a good idea for a better name, maybe "1to1", >>> "linear", "premapped" ? >> >> "identity"? > > I think that would be wrong, but thanks for trying to help :) > > The address on the device side is sometimes (often?) offset from the CPU > address. So eg. the device can DMA to RAM address 0x0 using address > 0x800000000000000. > > Identity would imply 0 == 0 etc. > > I think "bijective" is the correct term, but that's probably a bit > esoteric. OK, didn't know about the offset. Then "linear" is what we tend to use, right? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds