From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 035A7364925; Wed, 24 Jun 2026 11:38:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782301083; cv=none; b=ern0Ohy1fSX9Z4NSww8d2O6QB96n5ky99trjcp08rJZKfaNjjUFuyntNYqOzZy9OD/xn7A4MdaH4C1H3cYsDfskXn12tjOMG3DxpnQv8+Cz0XrE/eqI47Co/b6MeiV9fHCV9bQ8k5A8y/XMrtkxA0UJQ+sfZAnDzYu9F6bhpqpY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782301083; c=relaxed/simple; bh=3GSHxeyT9112m6bK0WlZR3PJhHo19/qNalU73sKaeaU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WD4aYwC3DxUCA2OLiYOQHGvp4vUFwgIwaRhCSVMj65EMjnPtaNC9Xo7kOjE+VXU4i83bpN+9eeLbCiDWKZFBkblME51jdwaMlfdTLp1Jd2JfPLemSy2dRMhXYYpZDo4+dEqxQRH1ZgAZaNefcoYCzWeJUzhzylJtdpPbnNzMXGw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=CExy3swe; arc=none smtp.client-ip=192.198.163.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="CExy3swe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1782301082; x=1813837082; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=3GSHxeyT9112m6bK0WlZR3PJhHo19/qNalU73sKaeaU=; b=CExy3swexoGZozC6srRLbYuXqfVy5nmTAO1xkYw+P6z6we/M3FRJauvN Oyyemt114pAeOcBnK2JecZ1VbEgqymFFQ9Vo5Rlk219KZGpOoAGfbnDuo CowkqxgHPA/hJIz+E0X2tbD9ISB+Xc3jBXwtoX6YUvD+WVnt+/ALKIXoN tcN4y3fiXz54SbsGXnbbcoN8GbcqJjyQsEq0UJ118JCrXy3/ATly3pJHe QzKzE1pavVIEe+Ju4Zvj0TQL+5mU+lyS+/SszUCkc6VS/pCpP90hLVSJf QlKNb9JWnjkBzP0nsI8hUplv8Pb6qRWp3ZLeR4Qp5IyXR9a7TPLxG8tgq Q==; X-CSE-ConnectionGUID: B3nXrlqmTrK3vABsxl4LoQ== X-CSE-MsgGUID: Cj4SdtZGTqKQl/VG7F224A== X-IronPort-AV: E=McAfee;i="6800,10657,11826"; a="82173079" X-IronPort-AV: E=Sophos;i="6.24,222,1774335600"; d="scan'208";a="82173079" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2026 04:38:00 -0700 X-CSE-ConnectionGUID: F7kbfVG+Rje15kanj0Bhxw== X-CSE-MsgGUID: T9ycpteGSpGWUGGDxPY2pA== X-ExtLoop1: 1 Received: from kniemiec-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.156]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2026 04:37:58 -0700 Date: Wed, 24 Jun 2026 14:37:56 +0300 From: Andy Shevchenko To: Paul Geurts Cc: jic23@kernel.org, dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, tobias.sperling@softing.com Subject: Re: [PATCH v3] iio: ti-ads7138: Disable STATS_EN bit while reading conversion results Message-ID: References: <20260624080131.3669357-1-paul.geurts@prodrive-technologies.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260624080131.3669357-1-paul.geurts@prodrive-technologies.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Wed, Jun 24, 2026 at 10:01:31AM +0200, Paul Geurts wrote: > There is a data race in reading the STATS registers, resulting in wrong > data being read. When the data in the RECENT register switches between > 0x24F0 and 0x2500, occasionally value 0x2400 or 0x25F0 is read. This > happens when the value is updated inbetween reading MSB and LSB. > > Disable the update of the channel stats before reading the values, for > registers MIN, MAX and RECENT. It seems the commit message still needs some elaboration as you explained in the previous version thread. > Signed-off-by: Paul Geurts > Fixes: 93a39542d3c3 ("iio: adc: Add driver for ADS7128 / ADS7138") ... > case IIO_CHAN_INFO_RAW: > + /* Disable statistics update so the value is not updated mid read */ > + ret = ads7138_i2c_clear_bit(data->client, ADS7138_REG_GENERAL_CFG, > + ADS7138_GENERAL_CFG_STATS_EN); > + if (ret) > + return ret; > ret = ads7138_i2c_read_block(data->client, > ADS7138_REG_RECENT_LSB_CH(chan->channel), > values, ARRAY_SIZE(values)); > if (ret) > return ret; > + /* Enable statistics update after read */ > + ret = ads7138_i2c_set_bit(data->client, ADS7138_REG_GENERAL_CFG, > + ADS7138_GENERAL_CFG_STATS_EN); > + if (ret) > + return ret; > > *val = get_unaligned_le16(values); > return IIO_VAL_INT; > case IIO_CHAN_INFO_PEAK: > + /* Disable statistics update so the value is not updated mid read */ > + ret = ads7138_i2c_clear_bit(data->client, ADS7138_REG_GENERAL_CFG, > + ADS7138_GENERAL_CFG_STATS_EN); > + if (ret) > + return ret; > ret = ads7138_i2c_read_block(data->client, > ADS7138_REG_MAX_LSB_CH(chan->channel), > values, ARRAY_SIZE(values)); > if (ret) > return ret; > + /* Enable statistics update after read */ > + ret = ads7138_i2c_set_bit(data->client, ADS7138_REG_GENERAL_CFG, > + ADS7138_GENERAL_CFG_STATS_EN); > + if (ret) > + return ret; > > *val = get_unaligned_le16(values); > return IIO_VAL_INT; > case IIO_CHAN_INFO_TROUGH: > + /* Disable statistics update so the value is not updated mid read */ > + ret = ads7138_i2c_clear_bit(data->client, ADS7138_REG_GENERAL_CFG, > + ADS7138_GENERAL_CFG_STATS_EN); > + if (ret) > + return ret; > ret = ads7138_i2c_read_block(data->client, > ADS7138_REG_MIN_LSB_CH(chan->channel), > values, ARRAY_SIZE(values)); > if (ret) > return ret; > + /* Enable statistics update after read */ > + ret = ads7138_i2c_set_bit(data->client, ADS7138_REG_GENERAL_CFG, > + ADS7138_GENERAL_CFG_STATS_EN); > + if (ret) > + return ret; > > *val = get_unaligned_le16(values); > return IIO_VAL_INT; This adds a lot of duplication? Can we have a wrapper on top of _i2c_read_block()? _i2c_read_statistics(client, reg, values, values_len) -- With Best Regards, Andy Shevchenko