From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH 16/67] powerpc: rename dma_direct_ to dma_nommu_ Date: Wed, 3 Jan 2018 08:49:35 +0100 Message-ID: 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=dg1gZQ0XTPl5ik865QhgMxj2iYnvoVLLg0Ri4903uJ4=; b=UQUCMDYTa6Xir3yzlWynpdu5ZxwVqJkJqkGHy9g61baXK0r6dv8OcyPAGJ+1WoxIwS IDsSaywI5gpGGex2l+3JD9ZfHtzLePQS13BKIe8nXZ4GhunrN83t+KO9A8+HppZ1a+8e dOiFjt0Qj0aKNR67MQWmJH2YwNL4bxRdhj92HDX4muLFujZQ7XWovpYKMhNXFwpcz8tX tRg6wY90t4s2xBD5NHiz4m3BfRe+wF9QVZdazO0cPDmQwpUunuyoR9PQMj58oLJQbM62 kQaGI9XnmEtm3arUBS+KLMzGtLcJ4eJe6mdi8QZgrgsxMCVzWcXrsv9y+4woGCUhGCCp H+tg== In-Reply-To: <87h8s3cvel.fsf-W0DJWXSxmBNbyGPkN3NxC2scP1bn1w/D@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Michael Ellerman Cc: Linux MIPS Mailing List , linux-ia64-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linux-sh list , sparclinux , Guan Xuetao , Christoph Hellwig , Linux-Arch , linux-s390 , linux-c6x-dev-jPsnJVOj+W6hPH1hqNUYSQ@public.gmane.org, "open list:QUALCOMM HEXAGON..." , the arch/x86 maintainers , arcml , adi-buildroot-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-m68k , patches-q3qR2WxjNRFS9aJRtSZj7A@public.gmane.org, "open list:METAG ARCHITECTURE" , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Michal Simek , Cris , Parisc List , Linux Kernel Mailing List , io 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-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.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