From patchwork Mon Jan 29 17:01:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13536072 Received: from aposti.net (aposti.net [89.234.176.197]) (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 941F5156962; Mon, 29 Jan 2024 17:02:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=89.234.176.197 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706547739; cv=none; b=GQ2Yyk4BY8UlEDpSCCAeDP4rQvK9EchziUc1rog0KSLCIHkZ6cJYZrnGwhII2DxAu4/GV9410g7Z40a5nL7NdL+sGXA3QwiSKuHieQrF7CjdTL5Uz0Fkl9HM4J2//Tfval5NviWGEgwg5JlUDRatmInwmCEyOw0YYf23ys6lZAw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706547739; c=relaxed/simple; bh=UJuDdpqpkjZJu/xNA1oILYJCsR4XV+J+vNBzHrUjiX4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=FoWZ9yaDTeaKzJirCsP1BE7hnhmv+QafzZR+kxaAP/y1SQUieLWZbqTohJsjG5uT0SG62GAu4gRl4B9m9opxt5CHVIKZ3O1bBq4YKuOSxfsQdh5BIMlpdHZmN/UAy5z0QZ8yUdVA8PoGpX+eRdhSNBUto9enwZgPJhb2QynlMEs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net; spf=pass smtp.mailfrom=crapouillou.net; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b=W7+npEzB; arc=none smtp.client-ip=89.234.176.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=crapouillou.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=crapouillou.net header.i=@crapouillou.net header.b="W7+npEzB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1706547735; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=UdxfhIPu1xHyG67FyRRevHrBT0ztFFCyHigeaYJvTDo=; b=W7+npEzBgGM0o8a7SHbyU6mF3GylmXNJJ8kTUn9FVMtH+5ggUp+e/cbweUryu9H+W0+PAQ vK3qpWhsITPG6Q2GGBsAqGuwNH5jUndpZvhfHmvkdsptWaGZeOtIbzmscoFvxEiMarHjXZ uS1DTilxDYGxydi6FIx+OKkDnE9pGaQ= From: Paul Cercueil To: Jonathan Cameron , Jonathan Corbet , Lars-Peter Clausen , Vinod Koul , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= Cc: Daniel Vetter , Nuno Sa , Michael Hennerich , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, linux-iio@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Paul Cercueil Subject: [PATCH v6 0/6] iio: new DMABUF based API, v6 Date: Mon, 29 Jan 2024 18:01:55 +0100 Message-ID: <20240129170201.133785-1-paul@crapouillou.net> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi Jonathan, This is the v6 of my patchset that introduces a new interface based on DMABUF objects. The code was updated quite a bit, using the feedback on the list for this patchset but also the feedback I received on the FunctionFS patchset that I'm working on upstreaming in parallel [1] where the DMABUF handling code is very similar. See below for the full changelog. I decided to drop the scope-based memory management for dma_buf and I hope you are OK with that. Christian wants the patch(es) to support scope-based memory management in dma-buf as a separate patchset; once it's in, I will gladly send a follow-up patch to use __free() where it makes sense. For performance numbers, I'll point you to the cover letter for my v5 patchset [2]. This patchset was based on next-20240129. Cheers, -Paul [1] https://lore.kernel.org/all/20230322092118.9213-1-paul@crapouillou.net/ [2] https://lore.kernel.org/linux-iio/219abc43b4fdd4a13b307ed2efaa0e6869e68e3f.camel@gmail.com/T/ --- Changelog: * [2/6]: - Use new prototype for axi_dmac_alloc_desc() as it changed upstream * [3/6]: - Remove dead code in iio_dma_resv_lock() - Fix non-block actually blocking - Cache dma_buf_attachment instead of mapping/unmapping it for every transfer - Return -EINVAL instead of IIO_IOCTL_UNHANDLED for unknown ioctl - Make .block_enqueue() callback take a dma_fence pointer, which will be passed to iio_buffer_signal_dmabuf_done() instead of the dma_buf_attachment; and remove the backpointer from the priv structure to the dma_fence. - Use dma_fence_begin/end_signalling in the dma_fence critical sections - Unref dma_fence and dma_buf_attachment in worker, because they might try to lock the dma_resv, which would deadlock. - Add buffer ops to lock/unlock the queue. This is motivated by the fact that once the dma_fence has been installed, we cannot lock anything anymore - so the queue must be locked before the dma_fence is installed. - Use 'long retl' variable to handle the return value of dma_resv_wait_timeout() - Protect dmabufs list access with a mutex - Rework iio_buffer_find_attachment() to use the internal dmabufs list, instead of messing with dmabufs private data. - Add an atomically-increasing sequence number for fences * [4/6]: - Update iio_dma_buffer_enqueue_dmabuf() to take a dma_fence pointer - Pass that dma_fence pointer along to iio_buffer_signal_dmabuf_done() - Add iio_dma_buffer_lock_queue() / iio_dma_buffer_unlock_queue() - Do not lock the queue in iio_dma_buffer_enqueue_dmabuf(). The caller will ensure that it has been locked already. - Replace "int += bool;" by "if (bool) int++;" - Use dma_fence_begin/end_signalling in the dma_fence critical sections - Use one "num_dmabufs" fields instead of one "num_blocks" and one "num_fileio_blocks". Make it an atomic_t, which makes it possible to decrement it atomically in iio_buffer_block_release() without having to lock the queue mutex; and in turn, it means that we don't need to use iio_buffer_block_put_atomic() everywhere to avoid locking the queue mutex twice. - Use cleanup.h guard(mutex) when possible - Explicitely list all states in the switch in iio_dma_can_enqueue_block() - Rename iio_dma_buffer_fileio_mode() to iio_dma_buffer_can_use_fileio(), and add a comment explaining why it cannot race vs. DMABUF. * [5/6]: - Populate .lock_queue / .unlock_queue callbacks - Switch to atomic memory allocations in .submit_queue, because of the dma_fence critical section - Make sure that the size of the scatterlist is enough --- Paul Cercueil (6): dmaengine: Add API function dmaengine_prep_slave_dma_vec() dmaengine: dma-axi-dmac: Implement device_prep_slave_dma_vec iio: core: Add new DMABUF interface infrastructure iio: buffer-dma: Enable support for DMABUFs iio: buffer-dmaengine: Support new DMABUF based userspace API Documentation: iio: Document high-speed DMABUF based API Documentation/iio/dmabuf_api.rst | 54 ++ Documentation/iio/index.rst | 2 + drivers/dma/dma-axi-dmac.c | 40 ++ drivers/iio/buffer/industrialio-buffer-dma.c | 181 ++++++- .../buffer/industrialio-buffer-dmaengine.c | 58 ++- drivers/iio/industrialio-buffer.c | 462 ++++++++++++++++++ include/linux/dmaengine.h | 25 + include/linux/iio/buffer-dma.h | 31 ++ include/linux/iio/buffer_impl.h | 33 ++ include/uapi/linux/iio/buffer.h | 22 + 10 files changed, 891 insertions(+), 17 deletions(-) create mode 100644 Documentation/iio/dmabuf_api.rst