From patchwork Mon Aug 7 11:21:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Cercueil X-Patchwork-Id: 13344017 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 961E3C001DB for ; Mon, 7 Aug 2023 11:59:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233020AbjHGL70 (ORCPT ); Mon, 7 Aug 2023 07:59:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233127AbjHGL7X (ORCPT ); Mon, 7 Aug 2023 07:59:23 -0400 Received: from aposti.net (aposti.net [89.234.176.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E292106; Mon, 7 Aug 2023 04:59:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=crapouillou.net; s=mail; t=1691407284; 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=ijYexI5QmdWQ0kvS0dVtdtyvZPj2CtQpyXkKIil5a8I=; b=zHVPC15KEWG1gbOY+NqxDYvWE6TtwuWRG1btnF/NDRyQnbKSEQ3h24ruJ8yS81DSkW58dd g5UgpThZwHpHfj4YPDwYGj/Wb9FFOuktHD2FuDzhq7GlAoDJp8r9vfxmFI9flk4iefN1Im AiXkuWvvjdWOYrDqkcwt0Q1bg/LoPoA= From: Paul Cercueil To: Jonathan Cameron Cc: Lars-Peter Clausen , Michael Hennerich , =?utf-8?q?Nuno_S=C3=A1?= , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Cercueil Subject: [PATCH v4 0/6] iio: Add buffer write() support Date: Mon, 7 Aug 2023 13:21:07 +0200 Message-Id: <20230807112113.47157-1-paul@crapouillou.net> MIME-Version: 1.0 X-Spam: Yes Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org [V3 was: "iio: new DMABUF based API, v3"][1] Hi Jonathan, This is a subset of my patchset that introduced a new interface based on DMABUF objects [1]. It adds write() support to the IIO buffer infrastructure. The reason it is not the full IIO-DMABUF patchset, is because you requested performance benchmarks - and our current numbers are barely better (~ +10%) than the fileio interface. There is a good reason for that: V3 of the patchset switched from having the IIO core creating the DMABUFs backed by physically contiguous memory, to having the IIO core being a simple DMABUF importer, and having the DMABUFs created externally. We now use the udmabuf driver to create those, and they are allocated from paged memory. While this works perfectly fine, our buffers are now cut in 4 KiB chunks (pages), non-contiguous in memory, which causes the DMA hardware to create an IRQ storm, as it raises an interrupt after each 4 KiB in the worst case scenario. Anyway, this is not directly a problem of the IIO-DMABUF code - but I can't really upstream a shiny new interface that I claim is much faster, without giving numbers. So while we fix this (either by updating the DMA IP and driver to support scatter-gather, or by hacking something quick to give us physically contiguous DMABUFs just for the benchmark), I thought it would make sense to upstream the few patches of the V3 patchset that are needed for the IIO-DMABUF interface but aren't directly related. As for write() support, Nuno (Cc'd) said he will work on upstreaming the DAC counterpart of adc/adi-axi-adc.c in the next few weeks, so there will be a user for the buffer write() support. I hope you are okay with this - otherwise, we can just wait until this work is done and submit it all at once. Changelog since v3: - [PATCH 2/6] is new; - [PATCH 3/6]: Drop iio_dma_buffer_space_available() function, and update patch description accordingly; - [PATCH 6/6]: .space_available is now set to iio_dma_buffer_usage (which is functionally the exact same). Cheers, -Paul [1] https://lore.kernel.org/all/20230403154800.215924-1-paul@crapouillou.net/ Alexandru Ardelean (1): iio: buffer-dma: split iio_dma_buffer_fileio_free() function Paul Cercueil (5): iio: buffer-dma: Get rid of outgoing queue iio: buffer-dma: Rename iio_dma_buffer_data_available() iio: buffer-dma: Enable buffer write support iio: buffer-dmaengine: Support specifying buffer direction iio: buffer-dmaengine: Enable write support drivers/iio/adc/adi-axi-adc.c | 3 +- drivers/iio/buffer/industrialio-buffer-dma.c | 187 ++++++++++++------ .../buffer/industrialio-buffer-dmaengine.c | 28 ++- include/linux/iio/buffer-dma.h | 11 +- include/linux/iio/buffer-dmaengine.h | 5 +- 5 files changed, 160 insertions(+), 74 deletions(-)