From patchwork Mon Mar 3 16:02:49 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Ripard X-Patchwork-Id: 13999088 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D7314C282CD for ; Mon, 3 Mar 2025 16:02:55 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6DCAA10E482; Mon, 3 Mar 2025 16:02:55 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="P1C9o2ia"; dkim-atps=neutral Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8361710E482 for ; Mon, 3 Mar 2025 16:02:54 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 1DEB15C5A1B; Mon, 3 Mar 2025 16:00:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44E5EC4CED6; Mon, 3 Mar 2025 16:02:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741017772; bh=VloWLNuJy+a+QMiYC5t2AH/V4T4fUJVth/jJq4Qzt9o=; h=From:To:Cc:Subject:Date:From; b=P1C9o2iawqT4rduu7fga8AP5SQKrG7Dm8sgPxPMbfCjQJK20NYWGKFD1Pk3wFPZSr cAGlI2HmWKxlMF+JLUnRHsO3agzJXu9cAHGRdlJPGCeL4J6le57XcnQdOyoFj2d8Cv Dk9sj78CCyTpBNcpSue988dENnggywPMpBacGvu9OjBkngYovq2QL9XbZkA70S6Sxe CohGyL8n8jY4C+NaNr/O4yR9XWJJfzQPPMGqIhHo78wFqPJtasolzBOlFd+CdxGql1 dsOp0mRYny4LVhTFGr9a4sE3HWMT7Yt0ByodRxhp6FjaTa8zR6fqlPYv+f9buKHMWW t+eyBjgi2wxFg== From: Maxime Ripard To: Jonathan Corbet , Sumit Semwal Cc: Benjamin Gaignard , Brian Starkey , John Stultz , "T . J . Mercier" , =?utf-8?q?Christian_K=C3=B6nig?= , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-doc@vger.kernel.org, Maxime Ripard Subject: [PATCH v3] Documentation: dma-buf: heaps: Add heap name definitions Date: Mon, 3 Mar 2025 17:02:49 +0100 Message-ID: <20250303160249.118549-1-mripard@kernel.org> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Following a recent discussion at last Plumbers, John Stultz, Sumit Sewal, TJ Mercier and I came to an agreement that we should document what the dma-buf heaps names are expected to be, and what the buffers attributes you'll get should be documented. Let's create that doc to make sure those attributes and names are guaranteed going forward. Signed-off-by: Maxime Ripard --- Changes from v2: - Remove exhaustive list of names for platforms, and just mention the alternatives. - Add MAINTAINERS entry Changes from v1: - Add the mention that the cma / reserved heap is optional. --- Documentation/userspace-api/dma-buf-heaps.rst | 25 +++++++++++++++++++ Documentation/userspace-api/index.rst | 1 + MAINTAINERS | 1 + 3 files changed, 27 insertions(+) create mode 100644 Documentation/userspace-api/dma-buf-heaps.rst diff --git a/Documentation/userspace-api/dma-buf-heaps.rst b/Documentation/userspace-api/dma-buf-heaps.rst new file mode 100644 index 000000000000..5b92d69646f6 --- /dev/null +++ b/Documentation/userspace-api/dma-buf-heaps.rst @@ -0,0 +1,25 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================== +Allocating dma-buf using heaps +============================== + +Dma-buf Heaps are a way for userspace to allocate dma-buf objects. They are +typically used to allocate buffers from a specific allocation pool, or to share +buffers across frameworks. + +Heaps +===== + +A heap represent a specific allocator. The Linux kernel currently supports the +following heaps: + + - The ``system`` heap allocates virtually contiguous, cacheable, buffers + + - The ``cma`` heap allocates physically contiguous, cacheable, + buffers. Only present if a CMA region is present. Such a region is + usually created either through the kernel commandline through the + `cma` parameter, a memory region Device-Tree node with the + `linux,cma-default` property set, or through the `CMA_SIZE_MBYTES` or + `CMA_SIZE_PERCENTAGE` Kconfig options. Depending on the platform, it + might be called ``reserved``, ``linux,cma``, or ``default-pool``. diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index b1395d94b3fd..9cbe4390c872 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -42,10 +42,11 @@ Devices and I/O .. toctree:: :maxdepth: 1 accelerators/ocxl + dma-buf-heaps dma-buf-alloc-exchange gpio/index iommufd media/index dcdbas diff --git a/MAINTAINERS b/MAINTAINERS index 8e0736dc2ee0..ef0364e65aef 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6911,10 +6911,11 @@ R: T.J. Mercier L: linux-media@vger.kernel.org L: dri-devel@lists.freedesktop.org L: linaro-mm-sig@lists.linaro.org (moderated for non-subscribers) S: Maintained T: git https://gitlab.freedesktop.org/drm/misc/kernel.git +F: Documentation/userspace-api/dma-buf-heaps.rst F: drivers/dma-buf/dma-heap.c F: drivers/dma-buf/heaps/* F: include/linux/dma-heap.h F: include/uapi/linux/dma-heap.h F: tools/testing/selftests/dmabuf-heaps/