From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 6241D470E8C; Fri, 2 Oct 2026 09:26:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790933166; cv=none; b=eVJOCTUH2Q9fTOEG3ss969kozpCWpVjXegB/7YudhSfCjHzby7dxnJpaiFIdYm//0Qn2D6v2uKxsCFKD/hwO8qKQI6gtjCjTtLowbDXWOMeUsXNlyD1ZOoC8uxqJ6ANy9FNiolVsrakO8MMsjoseCtOkKH6VaiuFYa6ywoDXMis= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790933166; c=relaxed/simple; bh=cpOoc8HlZ3e2s+YZ6TdqKW93Dns2IJrqALwipRqPtPE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=e7N/Y5Ovs9BkegK1AgnDXpItaLZC/70WGkbqQ7Yf672Q/I/Uu5B4bEv4RaxkTyJ11RpPr7tjzOicyvciKyB1U2WpxiFF7NLL/GcFI+F1rAtciTthIfi0ioKkc+sJBj/icoQ7ZZsCCSSasdHBw6FdzekOlENRmwY7bNet15JRBGE= 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=W2H9gbgd; arc=none smtp.client-ip=192.198.163.19 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="W2H9gbgd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790933164; x=1822469164; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=cpOoc8HlZ3e2s+YZ6TdqKW93Dns2IJrqALwipRqPtPE=; b=W2H9gbgdFQyeJJa6lcsIyz8BB9SxU8M7yiSVYKKa8mUr8zwdOLfDrYmk dZ0L9jb1RhuH6Vvuz+4WZBQWNpFXGclwHDOoH22C1zeROc9voPoPpJXRA bGhy1B6DEWwUc7qcgmsBRp/y8o/9yjtHhWIB1IqE+P8gpP/zhqU8+/Zq7 Na2ciszFEhIGTN4RJ4Sd6GCHi0kFMynNi9wVYhywFlS+iQr7EknIMc827 gh8CnFVHHrD8ZDwPM2aelYwDuz3l8vzKjaXvHcyOgQZCQEwQi6Tzp64Wl sOB6KbzRLCWb8+cGRWmK7Cjp/2A6BQ+vodc9q1E5XXU6e4AUq/3NWvIt3 A==; X-CSE-ConnectionGUID: V56qQiB7RJ+aXHE88KBUgw== X-CSE-MsgGUID: tIypn9XSQ0qm7BweQ1geTg== X-IronPort-AV: E=McAfee;i="6800,10657,11922"; a="90599394" X-IronPort-AV: E=Sophos;i="6.27,136,1787036400"; d="scan'208";a="90599394" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2026 02:26:03 -0700 X-CSE-ConnectionGUID: ek2Qu9S4QuW+t5wyiK8Oxw== X-CSE-MsgGUID: Q/uArPbXQuGDlQfIGLVX4A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,136,1787036400"; d="scan'208";a="314199592" Received: from conormcd-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.244.188]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2026 02:25:57 -0700 Date: Fri, 2 Oct 2026 12:25:54 +0300 From: Andy Shevchenko To: Rupesh Majhi Cc: Andy Shevchenko , David Lechner , Eddie James , Jonathan Cameron , Nuno =?iso-8859-1?Q?S=E1?= , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Sashiko , stable@vger.kernel.org Subject: Re: [PATCH v3] iio: pressure: dps310: fix overflow in pressure compensation Message-ID: References: <20261001121616.109973-1-zoone.rupert@gmail.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: <20261001121616.109973-1-zoone.rupert@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Thu, Oct 01, 2026 at 03:16:16PM +0300, Rupesh Majhi wrote: > p^3 * c30 and t * p^2 * c21 overflow s64 at most oversampling ratios, > and pressure comes out about 150 Pa low on a DPS310 here. > > Use Horner form, dividing by scale factor at each step. Overflow then > needs a raw value far outside sensor range and returns -ERANGE. > > Checked against datasheet formula at all eight ratios. Reviewed-by: Andy Shevchenko ... > + /* Section 4.9.1 of the DPS310 spec, Horner form to avoid overflow */ > + if (!dps310_horner_step(&prs, data->c30, p, kp) || > + !dps310_horner_step(&prs, data->c20, p, kp) || > + !dps310_horner_step(&prs, data->c10, p, kp) || > + !dps310_horner_step(&tmp, data->c21, p, kp) || > + !dps310_horner_step(&tmp, data->c11, p, kp) || > + !dps310_horner_step(&tmp, data->c01, t, kt)) > + return -ERANGE; Sorry for nit-picking, but since the above checks for overflow, perhaps makes sense to use actually -EOVERFLOW here. > - pressure += div_s64(rem, 1000000000LL); > - if (pressure < 0LL) > + pressure = data->c00 + div64_s64(prs + tmp, DPS310_CALC_ONE); > + if (pressure < 0) > return -ERANGE; -- With Best Regards, Andy Shevchenko