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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 CFE82C31E4B for ; Fri, 14 Jun 2019 14:20:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A36DF21537 for ; Fri, 14 Jun 2019 14:20:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="jEyWyusN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728842AbfFNOUT (ORCPT ); Fri, 14 Jun 2019 10:20:19 -0400 Received: from mail-wm1-f66.google.com ([209.85.128.66]:51826 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728633AbfFNOUS (ORCPT ); Fri, 14 Jun 2019 10:20:18 -0400 Received: by mail-wm1-f66.google.com with SMTP id 207so2574500wma.1 for ; Fri, 14 Jun 2019 07:20:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Ty57fS8FEMMkyXkp+DBY1O/OWs9quJnipD1xbuIqd/0=; b=jEyWyusNNcy/zIbSz97DCVXFWo6liOcR3UroHiqapt1gsw21z6NUzdxOP/hmEgFDBX t1czRS7WpYV+PhrzE3HFYeek6Du6wzUsF1/pN008841LWOFHasdvj6d+dFsDXf+hlrJU owQrDqnNU5/CublkS+8W0dU/rjeHgad6VMBxd8pnSRMEdPRJTt1X2bt1uaQJXAL1e/5q U/gmBDF5avTuXoNJUV7zOCQIGoZGpk0ulZIOp7Et4rU7grQ325ujdHK3kP5Y7lhQvg5X KWcolpqX/LJTn4nS4d4FeoGz8lrZ3u9tUQ3Ld6Z6/atadBGm/XGdJH91UL7cE7YTfnk/ qBtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Ty57fS8FEMMkyXkp+DBY1O/OWs9quJnipD1xbuIqd/0=; b=VcchbGXmjzuhDXKu9IwG1Lhu2/0XRv4RhMKahde7X5olDPUfq/HtLOUwRuFrf0Y3km /fT2ZotgeL7xHapPmjHmk4jwhwo15PWyEobNtKYKcmS41Pf4161vmlvTTgzKMW7PiT7P jffNtatR3///NHlw0+HK3Qj2haVx8aJljnmMZuVNiCPtqO2zVgodj62lur7GAMpwZilq /MkGbTPJTrBle7CcCq41JXLFPmKoh8212bTCpkwBgcqOKt8kjPVXphv4SewC9/4UTljR NGdGNAT0JbRj9wF8ejMPhCQcdCw6REon6EAUCidH6oOWZLhUtyxEnlHWdHoVq1SaBEQa YyAA== X-Gm-Message-State: APjAAAWmI6igyD1whPQWlv1/D5HFBVcD3RmliTpn7JbwwP7THcvvwJJo umkbXhT1bqQuqyvSK5JJAxiZug== X-Google-Smtp-Source: APXvYqxpNPUsDaAEg7ZHJS2hvOSurHBke9twjY/3loroMi7xipncRW4bBwmksKoG12q4fxRVq1yzYQ== X-Received: by 2002:a1c:b1d5:: with SMTP id a204mr118305wmf.101.1560522016576; Fri, 14 Jun 2019 07:20:16 -0700 (PDT) Received: from srini-hackbox.lan (cpc89974-aztw32-2-0-cust43.18-1.cable.virginm.net. [86.30.250.44]) by smtp.gmail.com with ESMTPSA id j7sm3990080wru.54.2019.06.14.07.20.15 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 14 Jun 2019 07:20:15 -0700 (PDT) From: Srinivas Kandagatla To: vkoul@kernel.org Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, sricharan@codeaurora.org, Srinivas Kandagatla Subject: [PATCH] dmaengine: qcom-bam: fix circular buffer handling Date: Fri, 14 Jun 2019 15:20:12 +0100 Message-Id: <20190614142012.31384-1-srinivas.kandagatla@linaro.org> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For some reason arguments to most of the circular buffers macros are used in reverse, tail is used for head and vice versa. This leads to bam thinking that there is an extra descriptor at the end and leading to retransmitting descriptor which was not scheduled by any driver. This happens after MAX_DESCRIPTORS (4096) are scheduled and done, so most of the drivers would not notice this, unless they are heavily using bam dma. Originally found this issue while testing SoundWire over SlimBus on DB845c which uses DMA very heavily for read/writes. Signed-off-by: Srinivas Kandagatla --- drivers/dma/qcom/bam_dma.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c index cb860cb53c27..43d7b0a9713a 100644 --- a/drivers/dma/qcom/bam_dma.c +++ b/drivers/dma/qcom/bam_dma.c @@ -350,8 +350,8 @@ static const struct reg_offset_data bam_v1_7_reg_info[] = { #define BAM_DESC_FIFO_SIZE SZ_32K #define MAX_DESCRIPTORS (BAM_DESC_FIFO_SIZE / sizeof(struct bam_desc_hw) - 1) #define BAM_FIFO_SIZE (SZ_32K - 8) -#define IS_BUSY(chan) (CIRC_SPACE(bchan->tail, bchan->head,\ - MAX_DESCRIPTORS + 1) == 0) +#define IS_BUSY(chan) (CIRC_SPACE(bchan->head, bchan->tail,\ + MAX_DESCRIPTORS) == 0) struct bam_chan { struct virt_dma_chan vc; @@ -806,7 +806,7 @@ static u32 process_channel_irqs(struct bam_device *bdev) offset /= sizeof(struct bam_desc_hw); /* Number of bytes available to read */ - avail = CIRC_CNT(offset, bchan->head, MAX_DESCRIPTORS + 1); + avail = CIRC_CNT(bchan->head, offset, MAX_DESCRIPTORS); list_for_each_entry_safe(async_desc, tmp, &bchan->desc_list, desc_node) { @@ -997,8 +997,7 @@ static void bam_start_dma(struct bam_chan *bchan) bam_apply_new_config(bchan, async_desc->dir); desc = async_desc->curr_desc; - avail = CIRC_SPACE(bchan->tail, bchan->head, - MAX_DESCRIPTORS + 1); + avail = CIRC_SPACE(bchan->head, bchan->tail, MAX_DESCRIPTORS); if (async_desc->num_desc > avail) async_desc->xfer_len = avail; -- 2.21.0