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=-7.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 1172BC169C4 for ; Wed, 6 Feb 2019 06:57:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D437A217F9 for ; Wed, 6 Feb 2019 06:57:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727913AbfBFG5w (ORCPT ); Wed, 6 Feb 2019 01:57:52 -0500 Received: from verein.lst.de ([213.95.11.211]:58147 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725897AbfBFG5v (ORCPT ); Wed, 6 Feb 2019 01:57:51 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id 218227F1C3; Wed, 6 Feb 2019 07:57:50 +0100 (CET) Date: Wed, 6 Feb 2019 07:57:50 +0100 From: Christoph Hellwig To: Thierry Reding Cc: Christoph Hellwig , Marek Szyprowski , Robin Murphy , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] dma-direct: Export dma_direct_alloc() and dma_direct_free() Message-ID: <20190206065749.GA23392@lst.de> References: <20190205110602.27717-1-thierry.reding@gmail.com> <20190205161036.GA782@lst.de> <20190205162057.GA29974@ulmo> <20190205163837.GA1222@lst.de> <20190205175611.GA7052@ulmo> <20190205180218.GB2882@lst.de> <20190205222912.GC1372@mithrandir> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190205222912.GC1372@mithrandir> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 05, 2019 at 11:29:12PM +0100, Thierry Reding wrote: > > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/drivers/gpu/host1x/cdma.c#n106 > > > > Yes, I think we I can come up with a nicer helper for that. > > One thing I could also try is to remove direct IOMMU API usage at least > from the host1x driver. I think this might work nowadays. > > For Tegra DRM we still need direct IOMMU API usage because we need to be > able to map into an IOMMU domain without knowing the struct device * > that we're mapping for (it could be needed by any of up to four display > controllers). For host1x we always only have one struct device *, so the > DMA mapping API should be good enough. If you can convert it to plain DMA API usage, please do. I did look into an IOMMU API memory allocator, and while we can do it easily for coherent devices, we need some arch hooks for non-coherent device support. With a pending series from me we have those for arm64, but 32-bit arm support will require a lot more work first.