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[23.128.96.18]) by mx.google.com with ESMTP id p5si2302168edx.145.2020.10.15.08.36.24; Thu, 15 Oct 2020 08:36:59 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@ffwll.ch header.s=google header.b=YEzGkNPj; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389677AbgJOPdk (ORCPT + 99 others); Thu, 15 Oct 2020 11:33:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389343AbgJOPdk (ORCPT ); Thu, 15 Oct 2020 11:33:40 -0400 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F9E9C061755 for ; Thu, 15 Oct 2020 08:33:38 -0700 (PDT) Received: by mail-wr1-x444.google.com with SMTP id e18so4023839wrw.9 for ; Thu, 15 Oct 2020 08:33:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=JHfVR15DmgNgHjEYT1vHwaXoRgLm3lEWzxDvCcdq+eU=; b=YEzGkNPjcWsWogVWz3QWffFRGWZD9E6EKg864hpltYi9b25EGfehPGSZVBj1A+HMl1 j79R9ryf8zrnmqi0v/SQKYh1CmueM5n9KdXPS6jZ8h7VxeCUl0XNMmKQbHYbqdoAcoSQ sYr1eA+AINxBZHMZawO8PinHCVnFYxphvWYxM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=JHfVR15DmgNgHjEYT1vHwaXoRgLm3lEWzxDvCcdq+eU=; b=eJDJcnchhwV7SP2ai710U/bNvlP6RPV5NJxkQ1cShOowJgbi1MdxpVdVRjXwqCwosH +ApvegHJbOYHH/v2zERGD9r1FqPKieYG5ujdGOhevGtI9fDzyuUqOS3JP1zaAy85TM3b vgrZwf9xZuyqLTB1f+hAOAsdXqyyI9wYr8ts0reJblD0fL+kOzobX0xo3nIJE1V2BTDN oF5hAB6h6AIONvpLgnyQ9IlSkp26lGMdoxB1YYgZHCwR3yTFB5mLalwGf5DNZDHW4KA0 WpFugl0q70UG9jOBpEj/SdnUkk2y4rqaDvG2HxzX8J7PSH7Dqgvbw/UBVPund9eDVURS yfmg== X-Gm-Message-State: AOAM533pqZHT2cqEC9w5fGOxNYzJo6X0osEtH+FaZQhYs8QIOdnN6/PN xomDdMGjb6Fz+z8kEXAK1GMdEg== X-Received: by 2002:adf:82ab:: with SMTP id 40mr4957151wrc.420.1602776017257; Thu, 15 Oct 2020 08:33:37 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id j101sm5918352wrj.9.2020.10.15.08.33.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Oct 2020 08:33:36 -0700 (PDT) Date: Thu, 15 Oct 2020 17:33:34 +0200 From: Daniel Vetter To: Christoph Hellwig Cc: 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, Daniel Vetter , "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: <20201015153334.GF438822@phenom.ffwll.local> Mail-Followup-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 References: <20201001002709.21361-3-jonathan@marek.ca> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201015065532.GA15371@infradead.org> X-Operating-System: Linux phenom 5.7.0-1-amd64 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). -Daniel > 2) force_dma_unencrypted() - we'd need to do an opt-out here, either > by a flag or by being smart and looking for an attached iommu on > the device > > > That way the > > device driver can make DMA API calls in the appropriate places that do the > > right thing either way, and only needs logic to decide whether to use the > > returned DMA addresses directly or ignore them if it knows they're > > overridden by its own IOMMU mapping. > > I'd be happy to review patches for this. -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch