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=-11.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 314FDC4360C for ; Thu, 10 Oct 2019 09:20:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0828F21D7C for ; Thu, 10 Oct 2019 09:20:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570699221; bh=7kyqtd1ZpG1jppKgJEY1RTSH0/DHkJq/p5pgsoY9vfI=; h=Subject:To:From:Date:List-ID:From; b=A/HJQHFV8fGbmImgqtHlGn8isXLj61kV3YkJ47x8WgjtMvqwFUs1UScT4EGaHWs6q MsvHJgPk9ZZRYrV/yHUXGAu/2HuPByUgtQrnX2ooNHENIPoKunHNWHR6JD772aH0hQ I7yvXS9GWwIo80WIGNqP7MscT7wo8BOfdE6JFPSs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387813AbfJJJUU (ORCPT ); Thu, 10 Oct 2019 05:20:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:42934 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387478AbfJJJUU (ORCPT ); Thu, 10 Oct 2019 05:20:20 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3E79A21D7B; Thu, 10 Oct 2019 09:20:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570699219; bh=7kyqtd1ZpG1jppKgJEY1RTSH0/DHkJq/p5pgsoY9vfI=; h=Subject:To:From:Date:From; b=Is1PVzNwHgyoj586//TIwtQOFCbVGS4B6Kjarqh45BWGv7ExxFJV+OoGXrTQj5p1d LwBNINFxE8c5FNl9AcV5fB28DzEELv5gWWH3sC2r4RsWgG7tkHu+R6fuwVkkHQwcHq pUeL3ptA2ox+VjuICSKqLJlEgmwlaKdtmXeTVioQ= Subject: patch "iio: adc: hx711: fix bug in sampling of data" added to staging-linus To: ak@it-klinger.de, Jonathan.Cameron@huawei.com, Stable@vger.kernel.org From: Date: Thu, 10 Oct 2019 11:20:04 +0200 Message-ID: <157069920481203@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled iio: adc: hx711: fix bug in sampling of data to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 4043ecfb5fc4355a090111e14faf7945ff0fdbd5 Mon Sep 17 00:00:00 2001 From: Andreas Klinger Date: Mon, 9 Sep 2019 14:37:21 +0200 Subject: iio: adc: hx711: fix bug in sampling of data 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 --- 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 88c7fe15003b..62e6c8badd22 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) -- 2.23.0