From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f54.google.com (mail-wm1-f54.google.com [209.85.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B3E13370D7B for ; Mon, 5 Oct 2026 06:46:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791182810; cv=none; b=JJmmmsCVrLcR8khm4aZt30M2J+QuT68wgo2TRlHA3VUOgwT+2hhwIYsB1qvERcJzhbHiTYNDDrUmsYqJ/r4F5/cTNbE8HenrLk7jb5rQ0COSFuoZ4xJSKaSENVPv+RW5beXcOlRaMhMTBEtNxensVL5ENEcoYfu0r/gaEP1XKiE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791182810; c=relaxed/simple; bh=5YTMgbdtfas9/Wgp0DfTQJZ86ha0EZMTqQX5JKE1wjs=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=XbId6Jt7EpxYHVEMPkRghhabu6l92rIaLbgEGAoj91XcXN5NVIGR23ZdRMRoxF7vgcZvdcXey8fFR/DDi8q/bHZxCYvRQGXChMiVDHPUGmkk4fm5vj39n1l7OcPNpSxKDAlpNE/ADbCc3/glHg2QJh3yLZo9uTm60OFPqoOIvWg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=kw7zT7CK; arc=none smtp.client-ip=209.85.128.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kw7zT7CK" Received: by mail-wm1-f54.google.com with SMTP id 5b1f17b1804b1-4a1626d6a6cso7860515e9.0 for ; Sun, 04 Oct 2026 23:46:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1791182807; x=1791787607; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=UDPEzA003wpyS4AK6a7pECjHcKEnmKef8YGoalZCMc8=; b=kw7zT7CKbKYytUUSLAfAUecE90cucLyPRbnpJtErosiX3D+BZ3zkZW70yTbll7sRiZ ULuVH8YCcURqqCqUw5WyQa3DHhUDhFu/86dLrWHd7a5pKfv/4CSApLd2oVNHYaXncvJP U4GsKvm74RFbq2TseyZ5bY1SdRo+/PvpEso72k0l8lrxN+PTE/86GOpsk3q/qWeaNGJa hRWTgyeCTLnu7UbQgLkOWQadedP1e4iltW4BhQhoXzq/RnOkL4sBX1gdBsDELyRMrmBO 4BFjdMxM+9FW4mCAbuMOPL5UpIWUXaIWtTpX6vPvi+v4VglgkJNREtENTVn4cE0UnkQX 7Rxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791182807; x=1791787607; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=UDPEzA003wpyS4AK6a7pECjHcKEnmKef8YGoalZCMc8=; b=B8R7IwGMv9TwYj2Uo6bLZgDbABB09oJ8hGffM60GPfyC2/24KYPrhXMEY650lMYwYu WCtBmpis9yOJf4Zvi+oH16lCIclNC5N2sYybbUwFj8zk86X0km6UZgptQ1NiaZvOBbV9 0RmFI5E8NQCNJxJKj9LkeltL/rIoekcQlCKadjFetHLvpEC4KWvDBpt4fqR6NRvQ9tk+ iSlPhJeHqj6f7YEXoNp5kC3b8vER6fQSr7i6RSZqlAbsfaZyz858L4qWrNYvnMikQEFH fd5HevWBKHo1sGdXKAj+h2L852QTpMlDW44YArpfj5IfxlOOdeqechYV/dLCQJmptpUK IJqQ== X-Forwarded-Encrypted: i=1; AKwUvBzf+WCVBvDa2Lr0QAmZ8hZyykAxmXt8acLWqfxGZQU6d34zMx8HS7ALO1+UWE87+lQH3hw5IqnNrmto7A==@vger.kernel.org X-Gm-Message-State: AFuF++kpRulhFza4L+KMGAdFuI9TBa4xqrPoHzXqJPQFRJh1vDyINV2Q TUrhRVycbh9aRPNTUTBIm9imo8963cIWOCiyUcWoVF9ELtKRhnGM0BZF X-Gm-Gg: AYBFou0MbX2W6S1+Z76OLdddFQSErM91sUtsL1F8SYs8ZtJHrZxhoxgr5EVecMgnPE7 D7TMscLS7rhXhnmgIstxAjQTUCdFkitS4KgbbD/6oFD6Z2vp9+1yBkKyxLwkyJTtQ2OCoFzFWRH XIL4QyPtLZJkTYQXagMIwjIdSE8ZdbAi0WubXDs+AjJoWQRmtoUWCV+HnBCIbvKZJeEjCB5a13x oIZYmHzHcDAl6UzdIRVwXdBMOWj7paNVEDBQzbEKe0jd1brcqgvgHjwIJUnJr+DzNyRcBC6lcNH RHx4/qDYlHtBFpl+ZPslSNTFPpBB52iZmtwKjbjmjBTcnFr5Ntpw2rQFlpsbxiC47WCyH2psPbH TZA2wx7wNyHWXe0ayXcl5Wmyq6WCLKi8FncsMGxJWdjuylffHWqX/0J9FD1E0jh2AEjFJgLuqGi g8Mob7/vTH1bYkEsFGwB/mzvR/mvKqK8k+o85q1VaQfp6vg/mmoPGJ/Tcn4yiE93yf+tUL6Hq9w 7bZ6MQarSI6NW3fHcBM6c4GLQJgMn34tMoIbiY8ODntTonauXYt2LXoRjbXpQcHyqCTvHNFv3JN cFCJ4fXMUnlcSPb/14Nify9VLEOX8h6QD+a4Mw/BbgLjDj5R41fi/kA7V1UmOquDB3FRJTol6Gi Q4LdGmpspIwyU X-Received: by 2002:a05:600c:6212:b0:49d:15b9:2a2a with SMTP id 5b1f17b1804b1-4a1680e9466mr94460155e9.10.1791182806529; Sun, 04 Oct 2026 23:46:46 -0700 (PDT) Received: from localhost.localdomain (dynamic-2a02-3100-b305-2001-39fa-3d24-821a-4eae.310.pool.telefonica.de. [2a02:3100:b305:2001:39fa:3d24:821a:4eae]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a027741586sm315273615e9.14.2026.10.04.23.46.44 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 04 Oct 2026 23:46:45 -0700 (PDT) From: Karl Mehltretter To: Sumit Semwal , =?UTF-8?q?Christian=20K=C3=B6nig?= Cc: Karl Mehltretter , Benjamin Gaignard , Brian Starkey , John Stultz , "T . J . Mercier" , Jason Gunthorpe , Dmitry Osipenko , Mauro Carvalho Chehab , Thierry Reding , Jonathan Hunter , Russell King , David Airlie , Simona Vetter , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 0/3] dma-buf: heaps: cma: respect the importer's maximum segment size Date: Mon, 5 Oct 2026 08:46:37 +0200 Message-Id: <20261005064640.7776-1-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The CMA heap builds attachment scatterlists without considering the importing device's maximum DMA segment size. When an entry exceeds that limit, DMA_API_DEBUG reports "mapping sg segment longer than device claims to support". Patch 3 uses the importer's limit. A corresponding udmabuf fix was posted in [1]. With patch 3, an importer that keeps the 64 KiB default gets a larger buffer in several entries. Two in-tree importers require a single entry and never set a limit: tegra-vde without an IOMMU domain, and armada. Patches 1 and 2 set an unlimited segment size there. I found them by searching the importers for checks on the number of entries and on the length of the first entry. etnaviv has a fast path for single-entry buffers but already declares a 2 GiB limit. Patches 1 and 2 are valid on their own and can go through their own trees. Patch 3 should only be applied after them, and is marked stable+noautosel for that reason. Tested in QEMU only, not on real hardware: patch 3 on a custom model of the SAM9X75 Curiosity, and all three patches on xilinx-zynq-a9 with tegra-vde and armada probing from stub device tree nodes. The notes of each patch have the details. [1] https://lore.kernel.org/r/20260929054835.94118-1-kmehltretter@gmail.com/ Karl Mehltretter (3): media: tegra-vde: set an unlimited DMA segment size drm/armada: set an unlimited DMA segment size dma-buf: heaps: cma: respect the device's maximum segment size drivers/dma-buf/heaps/cma_heap.c | 14 ++++++++++---- drivers/gpu/drm/armada/armada_drv.c | 3 +++ drivers/media/platform/nvidia/tegra-vde/vde.c | 2 ++ 3 files changed, 15 insertions(+), 4 deletions(-) base-commit: fe2ec83746e501645709761605c2464a44fd2929 -- 2.53.0