From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D24AC48BD7 for ; Tue, 25 Jun 2019 23:44:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B61620883 for ; Tue, 25 Jun 2019 23:44:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="auX38eXG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726468AbfFYXon (ORCPT ); Tue, 25 Jun 2019 19:44:43 -0400 Received: from mail-lf1-f67.google.com ([209.85.167.67]:44920 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726068AbfFYXon (ORCPT ); Tue, 25 Jun 2019 19:44:43 -0400 Received: by mail-lf1-f67.google.com with SMTP id r15so212701lfm.11; Tue, 25 Jun 2019 16:44:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=FW5zKtDHKyO5aAIruWb2V48ESwvyNPIVuCfJymbkDwM=; b=auX38eXGzDsU8d6XcVc1+ZvNlY1efuIdyjAi/jhsDMPRx1L7ZUMFfFQoyzjw3VX0jW H9f9xQ1w/nn1sIY5Mc6Mjr8AkcQCdPstdTcKMeAve3gw3mO5169Ymf5B+hm6SL777U2d yCI/ffMIguNj2ZpDbfLg+5UFrkOIt56Cldo3mNAHeGRAaCd34xjFEE3+hQcYxFLt18pd dBDk5Y/IKu5PTU8MC1sXtEc2kY6j8UGrV64RybmvVroGbRFkwzyqn8JVCIY028pkjkOz 9xT/9tkmV7gy8wzQV/N3GPn4NiEVd+GP2BRp0RSOQBoq7VctbJV9/mSnw/dopAZ4k71E yO0A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=FW5zKtDHKyO5aAIruWb2V48ESwvyNPIVuCfJymbkDwM=; b=EJhOWgwQw19xAIlfVdNkWi83AxnplarSEFKKHG8g3aGJHgB/+TFMGOa6D8jahY1xSV Fnmw9qDDivfkDdjgrebrXh6akyacqjGx7re/E0p926jdgT9FhxGtoYwHloCsLRqU/6X8 me9En/x9IIMNTfVrmjUYJNaYdQO/QrFvHfh6iHEDYubKf+uyo02WiE+SzA1syZATnuj8 gmfu3l0Ta8v1YJzjR5D+loFO33ID2gOZkak3yB3uKxdhaheNv5fAXn/XijVXHlppohTN 9cDwQmtRv7f1+4rkbATGuKMmiyEMu7q/cJhBodgBiNUxryymie4qCT8o9TCTKrejDXBi J0QA== X-Gm-Message-State: APjAAAVvOQ43A2VWODV/NoIrsZKBtTpyub9J8MjlxfRt/XmbPCvSJQp2 Nho0O+jM5sv7dgX2gKARXrcLubqF X-Google-Smtp-Source: APXvYqxWT33a4cYevVGk10Ptx4SPhrGxh3kj6aZ3PB/20ObRd0dqFIFPT62sO9LMikfgumwveR1uPQ== X-Received: by 2002:ac2:4901:: with SMTP id n1mr714681lfi.153.1561506279968; Tue, 25 Jun 2019 16:44:39 -0700 (PDT) Received: from [192.168.2.145] (ppp91-79-162-197.pppoe.mtu-net.ru. [91.79.162.197]) by smtp.googlemail.com with ESMTPSA id r20sm2041652ljr.20.2019.06.25.16.44.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Jun 2019 16:44:39 -0700 (PDT) Subject: Re: [PATCH v2] dmaengine: tegra-apb: Support per-burst residue granularity From: Dmitry Osipenko To: Jon Hunter , Laxman Dewangan , Vinod Koul , Thierry Reding , Ben Dooks Cc: dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190618115035.29250-1-digetx@gmail.com> <8f48fcba-df7c-a313-2f84-0fa896e4ccec@nvidia.com> <8470f28f-b903-c6ed-23bd-0cbd130f0798@gmail.com> Message-ID: <81648813-3a19-d390-fa9a-f2e0bf4e4d72@gmail.com> Date: Wed, 26 Jun 2019 02:44:38 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <8470f28f-b903-c6ed-23bd-0cbd130f0798@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 21.06.2019 0:58, Dmitry Osipenko пишет: > 20.06.2019 11:38, Jon Hunter пишет: >> >> On 18/06/2019 12:50, Dmitry Osipenko wrote: >>> Tegra's APB DMA engine updates words counter after each transferred burst >>> of data, hence it can report transfer's residual with more fidelity which >>> may be required in cases like audio playback. In particular this fixes >>> audio stuttering during playback in a chromiuim web browser. The patch is >>> based on the original work that was made by Ben Dooks. It was tested on >>> Tegra20 and Tegra30 devices. >>> >>> Link: https://lore.kernel.org/lkml/20190424162348.23692-1-ben.dooks@codethink.co.uk/ >>> Inspired-by: Ben Dooks >>> Signed-off-by: Dmitry Osipenko >>> --- >>> >>> Changelog: >>> >>> v2: Addressed review comments made by Jon Hunter to v1. We won't try >>> to get words count if dma_desc is on free list as it will result >>> in a NULL dereference because this case wasn't handled properly. >>> >>> The residual value is now updated properly, avoiding potential >>> integer overflow by adding the "bytes" to the "bytes_transferred" >>> instead of the subtraction. >>> >>> drivers/dma/tegra20-apb-dma.c | 33 ++++++++++++++++++++++++++------- >>> 1 file changed, 26 insertions(+), 7 deletions(-) >>> >>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c >>> index 79e9593815f1..fed18bc46479 100644 >>> --- a/drivers/dma/tegra20-apb-dma.c >>> +++ b/drivers/dma/tegra20-apb-dma.c >>> @@ -797,6 +797,28 @@ static int tegra_dma_terminate_all(struct dma_chan *dc) >>> return 0; >>> } >>> >>> +static unsigned int tegra_dma_sg_bytes_xferred(struct tegra_dma_channel *tdc, >>> + struct tegra_dma_sg_req *sg_req) >>> +{ >>> + unsigned long status, wcount = 0; >>> + >>> + if (!list_is_first(&sg_req->node, &tdc->pending_sg_req)) >>> + return 0; >>> + >>> + if (tdc->tdma->chip_data->support_separate_wcount_reg) >>> + wcount = tdc_read(tdc, TEGRA_APBDMA_CHAN_WORD_TRANSFER); >>> + >>> + status = tdc_read(tdc, TEGRA_APBDMA_CHAN_STATUS); >>> + >>> + if (!tdc->tdma->chip_data->support_separate_wcount_reg) >>> + wcount = status; >>> + >>> + if (status & TEGRA_APBDMA_STATUS_ISE_EOC) >>> + return sg_req->req_len; >>> + >>> + return get_current_xferred_count(tdc, sg_req, wcount); >>> +} >>> + >>> static enum dma_status tegra_dma_tx_status(struct dma_chan *dc, >>> dma_cookie_t cookie, struct dma_tx_state *txstate) >>> { >>> @@ -806,6 +828,7 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc, >>> enum dma_status ret; >>> unsigned long flags; >>> unsigned int residual; >>> + unsigned int bytes = 0; >>> >>> ret = dma_cookie_status(dc, cookie, txstate); >>> if (ret == DMA_COMPLETE) >>> @@ -825,6 +848,7 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc, >>> list_for_each_entry(sg_req, &tdc->pending_sg_req, node) { >>> dma_desc = sg_req->dma_desc; >>> if (dma_desc->txd.cookie == cookie) { >>> + bytes = tegra_dma_sg_bytes_xferred(tdc, sg_req); >>> ret = dma_desc->dma_status; >>> goto found; >>> } >>> @@ -836,7 +860,7 @@ static enum dma_status tegra_dma_tx_status(struct dma_chan *dc, >>> found: >>> if (dma_desc && txstate) { >>> residual = dma_desc->bytes_requested - >>> - (dma_desc->bytes_transferred % >>> + ((dma_desc->bytes_transferred + bytes) % >>> dma_desc->bytes_requested); >>> dma_set_residue(txstate, residual); >>> } >>> @@ -1441,12 +1465,7 @@ static int tegra_dma_probe(struct platform_device *pdev) >>> BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) | >>> BIT(DMA_SLAVE_BUSWIDTH_8_BYTES); >>> tdma->dma_dev.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV); >>> - /* >>> - * XXX The hardware appears to support >>> - * DMA_RESIDUE_GRANULARITY_BURST-level reporting, but it's >>> - * only used by this driver during tegra_dma_terminate_all() >>> - */ >>> - tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT; >>> + tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST; >>> tdma->dma_dev.device_config = tegra_dma_slave_config; >>> tdma->dma_dev.device_terminate_all = tegra_dma_terminate_all; >>> tdma->dma_dev.device_tx_status = tegra_dma_tx_status; >>> >> >> Looks good to me. Thanks for fixing! >> >> Reviewed-by: Jon Hunter > > Thanks to you too for the review :) > Please hold on this patch. I took another look at this and spotted unfortunate typo in the tests that I wrote and indeed wraparound happens before EOC bit is set, just like Ben told :( I'll be looking at this all again during next days. Looks like the EOC bit is set after a burst completion once hardware counter is reloaded.