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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 1E637CA9EA9 for ; Fri, 18 Oct 2019 22:24:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E662E20872 for ; Fri, 18 Oct 2019 22:24:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571437469; bh=wcM6TwOsJEJ4ba0dvvFQxuCQYRTD52M8/Wbqdh7BNoY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zY3eYma4E6mv0E4OenxfO37H93hdpTan3p6+wWG/mDwWiZE+BE33dGZPESvxhSGYO xm0kCXxtzaak4bj+3Gi1rqG0nMstCKea9qhEvgjrFD1O3WDZ8uXcim4NclNMss0TGM Ar+1N2MSq6wnPcglsagpZRr26BlTddO0PYN6P4bU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729028AbfJRWFB (ORCPT ); Fri, 18 Oct 2019 18:05:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:36736 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728978AbfJRWE6 (ORCPT ); Fri, 18 Oct 2019 18:04:58 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 047F52245D; Fri, 18 Oct 2019 22:04:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571436297; bh=wcM6TwOsJEJ4ba0dvvFQxuCQYRTD52M8/Wbqdh7BNoY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HR8nzIqIF8eH9WXTVTSNWVVj/up/FCqg2SsdY7mvZ56CmAC2/DoFVt1KaKgRPCWKN Zhss8wWmhvK8v6t0S+4zhllmDed8GJ5GNntnzeveWNQmEr93NSbl5vti8jPIoajqiI KEbt0UOOCx09PPi9wc8juG2nGs/s3hRtAMQZ7Cy4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Andreas Klinger , Stable@vger.kernel.org, Jonathan Cameron , Sasha Levin , linux-iio@vger.kernel.org Subject: [PATCH AUTOSEL 5.3 69/89] iio: adc: hx711: fix bug in sampling of data Date: Fri, 18 Oct 2019 18:03:04 -0400 Message-Id: <20191018220324.8165-69-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191018220324.8165-1-sashal@kernel.org> References: <20191018220324.8165-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Andreas Klinger [ Upstream commit 4043ecfb5fc4355a090111e14faf7945ff0fdbd5 ] Fix bug in sampling function hx711_cycle() when interrupt occures while PD_SCK is high. If PD_SCK is high for at least 60 us power down mode of the sensor is entered which in turn leads to a wrong measurement. Switch off interrupts during a PD_SCK high period and move query of DOUT to the latest point of time which is at the end of PD_SCK low period. This bug exists in the driver since it's initial addition. The more interrupts on the system the higher is the probability that it happens. Fixes: c3b2fdd0ea7e ("iio: adc: hx711: Add IIO driver for AVIA HX711") Signed-off-by: Andreas Klinger Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Sasha Levin --- drivers/iio/adc/hx711.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c index 88c7fe15003b7..62e6c8badd22a 100644 --- a/drivers/iio/adc/hx711.c +++ b/drivers/iio/adc/hx711.c @@ -100,14 +100,14 @@ struct hx711_data { static int hx711_cycle(struct hx711_data *hx711_data) { - int val; + unsigned long flags; /* * if preempted for more then 60us while PD_SCK is high: * hx711 is going in reset * ==> measuring is false */ - preempt_disable(); + local_irq_save(flags); gpiod_set_value(hx711_data->gpiod_pd_sck, 1); /* @@ -117,7 +117,6 @@ static int hx711_cycle(struct hx711_data *hx711_data) */ ndelay(hx711_data->data_ready_delay_ns); - val = gpiod_get_value(hx711_data->gpiod_dout); /* * here we are not waiting for 0.2 us as suggested by the datasheet, * because the oscilloscope showed in a test scenario @@ -125,7 +124,7 @@ static int hx711_cycle(struct hx711_data *hx711_data) * and 0.56 us for PD_SCK low on TI Sitara with 800 MHz */ gpiod_set_value(hx711_data->gpiod_pd_sck, 0); - preempt_enable(); + local_irq_restore(flags); /* * make it a square wave for addressing cases with capacitance on @@ -133,7 +132,8 @@ static int hx711_cycle(struct hx711_data *hx711_data) */ ndelay(hx711_data->data_ready_delay_ns); - return val; + /* sample as late as possible */ + return gpiod_get_value(hx711_data->gpiod_dout); } static int hx711_read(struct hx711_data *hx711_data) -- 2.20.1