From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 829F2606A326 for ; Thu, 29 Oct 2026 12:03:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=AoCWCuSU DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=AdT7vjX9hlZBYeDnKKDlyq+tnX7uZdKaSwbD6yyWOuU=; b=AoCWCuSUWlW5nmEhAqrJfRRb+c YX9gqE8crhHR4nsHVxHfKwofoqH/0d9IWQ86zRniJ0doTh+M8qBGfgmssuFXxkqbILdnhVQH+rhvB S5I2TQ57RtSMYsJISIACklbb8YN/7GOLywyC/uvQUSYmOG3M+7a5Zg5xxwzgCA8LJIEWujM44YZJE KLdcMXNRnj+1blrHH5EAwqR6FHBJA8zyew8Dz5jUuHJKByau3A9WwAoI6/1Gi4bkOW7lhr2YEyJ3q Ov0y/pgn7snTWsTKjRCtfxkNqirXay2LVLtU6V1pz0p+eAiCWb0mGd14Ea6fICGh7uaLS1sZtullM B3rxoPSQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMOr2-000000096sU-0uhA; Thu, 29 Oct 2026 12:03:36 +0000 Received: from hch by bombadil.infradead.org with local (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMOqy-000000096rb-2rgE; Thu, 29 Oct 2026 12:03:32 +0000 Date: Thu, 29 Oct 2026 05:03:32 -0700 From: Christoph Hellwig To: Mikko Perttunen Cc: Robin Murphy , Marek Szyprowski , "Joerg Roedel (AMD)" , Will Deacon , Russell King , Heiko Stuebner , Thierry Reding , David Airlie , Simona Vetter , Jonathan Hunter , Krishna Reddy , Krzysztof Kozlowski , Jason Gunthorpe , Peter Griffin , Alim Akhtar , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Yong Wu , Matthias Brugger , AngeloGioacchino Del Regno , Rob Clark , Geert Uytterhoeven , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org Subject: Re: [PATCH v3 00/10] Make the 32-bit ARM DMA API work with normal IOMMU DMA default domains (+ Tegra PoC) Message-ID: References: <20261026-b4-arm32-iommu-dma-cookie-v3-0-3901d74b1ff2@nvidia.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261026-b4-arm32-iommu-dma-cookie-v3-0-3901d74b1ff2@nvidia.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon, Oct 26, 2026 at 06:19:25PM +0900, Mikko Perttunen wrote: > Robin suggested [1] that instead of teaching the legacy path about > groups, we should explore modernizing the 32-bit ARM DMA code a bit by > making it use domain cookies and have the core code own the domains, as > is the case on other architectures. Still, ARM's own DMA code is kept to > support existing drivers and APIs that expect it, and because dma-iommu > is considered too big and unnecessary for 32-bit ARM. Now that the different domain handling is gone, what speaks against just using the generic dma-iommu code for arm32?