From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF12EC3A589 for ; Thu, 15 Aug 2019 18:54:03 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 584CC206C1 for ; Thu, 15 Aug 2019 18:54:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 584CC206C1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 468bG0663czDr3j for ; Fri, 16 Aug 2019 04:54:00 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 468bCr10BjzDqvW for ; Fri, 16 Aug 2019 04:52:08 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id 5E18068AFE; Thu, 15 Aug 2019 20:52:00 +0200 (CEST) Date: Thu, 15 Aug 2019 20:52:00 +0200 From: Christoph Hellwig To: "Koenig, Christian" Subject: Re: [PATCH 0/6] drm+dma: cache support for arm, etc Message-ID: <20190815185200.GA21407@lst.de> References: <215e5cb7-0fcf-48db-a656-817054dde420@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <215e5cb7-0fcf-48db-a656-817054dde420@email.android.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kate Stewart , Masayoshi Mizuma , "Maciej W. Rozycki" , Eric Biggers , Catalin Marinas , Imre Deak , dri-devel , Chris Wilson , Masahiro Yamada , Benjamin Gaignard , Mauro Carvalho Chehab , Will Deacon , Christoph Hellwig , Emil Velikov , Rob Clark , Paul Burton , Mike Rapoport , Geert Uytterhoeven , "moderated list:ARM64 PORT \(AARCH64 ARCHITECTURE\)" , Daniel Vetter , "open list:MIPS" , Linus Walleij , Robin Murphy , "open list:DRM DRIVER FOR MSM ADRENO GPU" , "Sharma, Deepak" , Joerg Roedel , Arnd Bergmann , Anshuman Khandual , Hauke Mehrtens , Jesper Dangaard Brouer , "Wolfram Sang \(Renesas\)" , "open list:LINUX FOR POWERPC \(32-BIT AND 64-BIT\)" , Alexios Zavras , Russell King , Doug Anderson , Thomas Gleixner , Sean Paul , Allison Randal , Ard Biesheuvel , Enrico Weigelt , open list , Rob Clark , Souptick Joarder , Greg Kroah-Hartman , Andrew Morton , "open list:DRM DRIVER FOR MSM ADRENO GPU" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Aug 15, 2019 at 06:48:39PM +0000, Koenig, Christian wrote: > Well, for the graphics case I absolutely need to keep the linear kernel mapping. Because for certain use cases the memory is accessed by the kernel all the time as well. Then don't set DMA_ATTR_NO_KERNEL_MAPPING. At least for x86 and arm64 we should be able to support uncached allocations easily even without that, and I plan to support that for your use case. But if the driver is explicitly saying it doesn't want a permanent kernel mapping it makes sense to (optionally if the architecture can easily do it) unmap the memory from the kernel linear mapping.