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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 95BF2C433DF for ; Thu, 15 Oct 2020 15:43:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 084F520723 for ; Thu, 15 Oct 2020 15:43:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qiOxssgQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731061AbgJOPnH (ORCPT ); Thu, 15 Oct 2020 11:43:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40448 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730957AbgJOPnH (ORCPT ); Thu, 15 Oct 2020 11:43:07 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EDC98C061755; Thu, 15 Oct 2020 08:43:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:To:From:Date:Sender:Reply-To:Cc: Content-Transfer-Encoding:Content-ID:Content-Description; bh=UfF27sEhMEzOUuKtPSUEIOacG1Uky8VuZ8tGa3014PI=; b=qiOxssgQW83wNoO58DAw8tk3KM 6/ParIJvMZcFbEexanutV1KdiUSZOc3afV+2l385wIqUCM9Bql2GiliQ7M12ViBDqRZMTv6GsgZ7i syWH7IiNDdCFjYdl9rmUk42ULFbtRTpf1BD1qC0MndqdpcL7hGW1qoHq9gVSH0A/HOkXMSTlwbcGf PjGyBfbQF5bpNnaIkY8JQWQiX1CW8OPnbXw5euPHZvPN/fnOYCHsTQ2Kpoq6UaDpavzkVc5nbMwFX GMHLA0c5pnv6/tjJra+LzV/VR7fzT+gd0EZL7JkRykOuyDTrvSIR6OOM8r+VjfPdu6RWp2HQ/8yDh ebdqRieQ==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kT5PA-00027N-RG; Thu, 15 Oct 2020 15:43:00 +0000 Date: Thu, 15 Oct 2020 16:43:00 +0100 From: Christoph Hellwig To: Christoph Hellwig , Robin Murphy , Jonathan Marek , David Airlie , freedreno@lists.freedesktop.org, open list , "open list:DRM DRIVER FOR MSM ADRENO GPU" , iommu@lists.linux-foundation.org, "open list:DRM DRIVER FOR MSM ADRENO GPU" , Sean Paul Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance Message-ID: <20201015154300.GA8047@infradead.org> References: <20201002075321.GA7547@infradead.org> <20201005082914.GA31702@infradead.org> <3e0b91be-e4a4-4ea5-7d58-6e71b8d51932@marek.ca> <20201006072306.GA12834@infradead.org> <148a1660-f0fc-7163-2240-6b94725342b5@marek.ca> <20201007062519.GA23519@infradead.org> <20201015065532.GA15371@infradead.org> <20201015153334.GF438822@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201015153334.GF438822@phenom.ffwll.local> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, Oct 15, 2020 at 05:33:34PM +0200, Daniel Vetter wrote: > On Thu, Oct 15, 2020 at 07:55:32AM +0100, Christoph Hellwig wrote: > > On Tue, Oct 13, 2020 at 02:42:38PM +0100, Robin Murphy wrote: > > > I still think this situation would be best handled with a variant of > > > dma_ops_bypass that also guarantees to bypass SWIOTLB, and can be set > > > automatically when attaching to an unmanaged IOMMU domain. > > > > dma_ops_bypass should mostly do the right thing as-is. swiotlb bouncing > > is triggered of two things: > > > > 1) the dma_mask. This is under control of the driver, and obviously > > if it is too small for a legit reason we can't just proceed > > Somewhat related, but is there a way to tell the dma-api to fail instead > of falling back to swiotlb? In many case for gpu drivers it's much better > if we fall back to dma_alloc_coherent and manage the copying ourselves > instead of abstracting this away in the dma-api. Currently that's "solved" > rather pessimistically by always allocating from dma_alloc_coherent if > swiotlb could be in the picture (at least for ttm based drivers, i915 just > falls over). Is this for the alloc_pages plus manually map logic in various drivers? They should switch to the new dma_alloc_pages API that I'll send to Linus for 5.10 soon.