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=-12.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 CF2CCC4727F for ; Wed, 23 Sep 2020 12:25:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E6B321D92 for ; Wed, 23 Sep 2020 12:25:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="fuqfqEXO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726552AbgIWMZD (ORCPT ); Wed, 23 Sep 2020 08:25:03 -0400 Received: from esa5.microchip.iphmx.com ([216.71.150.166]:53718 "EHLO esa5.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726513AbgIWMZD (ORCPT ); Wed, 23 Sep 2020 08:25:03 -0400 X-Greylist: delayed 426 seconds by postgrey-1.27 at vger.kernel.org; Wed, 23 Sep 2020 08:25:03 EDT DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1600863904; x=1632399904; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=QmuxF1k6JrlZgiNhVt0KMHpx0TS8HpqXkv0zvHy4YP4=; b=fuqfqEXO/8WMwMglwLLb0zvbageEvXZGg8wvfp/BuQKQ0SaebW3un+M2 VbitoNdJSmqwuRD4Yow4QxQQFV5aNpLjkzmk8n6ZWZNHNapGY/gCRVE6V CAiYRyeuHR0Ox0d44Z8LNHcbuswxUQzwBkHpLj2yXxRL3g59ZPOHzzRDK nLKQc72o0/x3WdcYTW0RV8NaLpfrTZx9/bCRyHExww8+2Jn+lTrFGI1Y8 da7XGT46crSh04Tl6t7Q5SVinY/8YPuOp/UI33Vzyp8zbZF5vU/97kfBY PqvVffhwBiSI+74KVZw6gJ9Zu3TXqsL0xevEed+GhbUyuYbyXnDJ+oUWl g==; IronPort-SDR: fjcb6KWeS9NeUAPNPl/nN/NLjSpbTnZei5ymP1HDxx6lRKrG50OQTwp2KgNaRbf8CSfPsgkybx Eam5i78MzduCr8RtPKel9XAkI+uO1vBdNaBLG8JfDI6wfOMEV5E4EwyC6qTzcJ2yQv/XCx1PqK h6/Guf524PLoA83Fnl62A3Nl9NjBVNmetZObd69J8Op8Pg+a2ROBOLHu+Vdoiu0Yf6IV3fKYMk oKl87jXDwYFaV3I33jQGs//NJ0DcgqE/oKxOa7fZmvjr1wapdwkjbIeRtsTvcI/cvJHVatYFw2 sPg= X-IronPort-AV: E=Sophos;i="5.77,293,1596524400"; d="scan'208";a="92080952" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa5.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 23 Sep 2020 05:17:57 -0700 Received: from chn-vm-ex04.mchp-main.com (10.10.85.152) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Wed, 23 Sep 2020 05:17:37 -0700 Received: from ROB-ULT-M18282.microchip.com (10.10.115.15) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server id 15.1.1979.3 via Frontend Transport; Wed, 23 Sep 2020 05:17:52 -0700 From: Eugen Hristev To: , CC: , , , Eugen Hristev Subject: [PATCH v2] iio: adc: at91-sama5d2_adc: fix DMA conversion crash Date: Wed, 23 Sep 2020 15:17:48 +0300 Message-ID: <20200923121748.49384-1-eugen.hristev@microchip.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After the move of the postenable code to preenable, the DMA start was done before the DMA init, which is not correct. The DMA is initialized in set_watermark. Because of this, we need to call the DMA start functions in set_watermark, after the DMA init, instead of preenable hook, when the DMA is not properly setup yet. Fixes: f3c034f61775 ("iio: at91-sama5d2_adc: adjust iio_triggered_buffer_{predisable,postenable} positions") Signed-off-by: Eugen Hristev --- Changes in v2: - check return value of buffer prepare, and in case of error, unwind DMA - validated by trying to force an error : # echo 100 > /sys/bus/iio/devices/iio\:device0/buffer/length # echo 100 > /sys/bus/iio/devices/iio\:device0/buffer/watermark # iio_generic_buffer -n fc030000.adc -t fc030000.adc-dev0-external_rising -c 5 iio device number being used is 0 iio trigger number being used is 0 /sys/bus/iio/deviciio io:device0 fc030000.adc-dev0-external_risingiio:device0: using dma0chan10 for rx DMA transfers iio iio:device0: continuing without DMA support 505.151367 983.715820 1352.709961 1485.644531 Original patch message: Hi, This crash is in the kernel since 5.8-rc1 Please have a look at discussion here: https://lore.kernel.org/linux-iio/CA+U=DsqRUtjjoe5nevP_wNxTgr27+O2V1h9w7d3QijBQ+5f3XA@mail.gmail.com/T/#t Thanks ! drivers/iio/adc/at91-sama5d2_adc.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c index de9583d6cddd..f94641193b98 100644 --- a/drivers/iio/adc/at91-sama5d2_adc.c +++ b/drivers/iio/adc/at91-sama5d2_adc.c @@ -884,7 +884,7 @@ static bool at91_adc_current_chan_is_touch(struct iio_dev *indio_dev) AT91_SAMA5D2_MAX_CHAN_IDX + 1); } -static int at91_adc_buffer_preenable(struct iio_dev *indio_dev) +static int at91_adc_buffer_prepare(struct iio_dev *indio_dev) { int ret; u8 bit; @@ -901,7 +901,7 @@ static int at91_adc_buffer_preenable(struct iio_dev *indio_dev) /* we continue with the triggered buffer */ ret = at91_adc_dma_start(indio_dev); if (ret) { - dev_err(&indio_dev->dev, "buffer postenable failed\n"); + dev_err(&indio_dev->dev, "buffer prepare failed\n"); return ret; } @@ -989,7 +989,6 @@ static int at91_adc_buffer_postdisable(struct iio_dev *indio_dev) } static const struct iio_buffer_setup_ops at91_buffer_setup_ops = { - .preenable = &at91_adc_buffer_preenable, .postdisable = &at91_adc_buffer_postdisable, }; @@ -1563,6 +1562,7 @@ static void at91_adc_dma_disable(struct platform_device *pdev) static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val) { struct at91_adc_state *st = iio_priv(indio_dev); + int ret; if (val > AT91_HWFIFO_MAX_SIZE) return -EINVAL; @@ -1586,7 +1586,15 @@ static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val) else if (val > 1) at91_adc_dma_init(to_platform_device(&indio_dev->dev)); - return 0; + /* + * We can start the DMA only after setting the watermark and + * having the DMA initialization completed + */ + ret = at91_adc_buffer_prepare(indio_dev); + if (ret) + at91_adc_dma_disable(to_platform_device(&indio_dev->dev)); + + return ret; } static int at91_adc_update_scan_mode(struct iio_dev *indio_dev, -- 2.25.1