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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30571ECAAD5 for ; Tue, 30 Aug 2022 19:22:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231299AbiH3TWa (ORCPT ); Tue, 30 Aug 2022 15:22:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230462AbiH3TW3 (ORCPT ); Tue, 30 Aug 2022 15:22:29 -0400 Received: from smtp-fw-80006.amazon.com (smtp-fw-80006.amazon.com [99.78.197.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10B4879A46; Tue, 30 Aug 2022 12:22:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1661887349; x=1693423349; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=7jM9bxUFTiRFdN9eRnLAR3tNYJTs9bs57sY6eoa56LY=; b=KrrF4f0AGaOWgbevgpIQ/SPBB5lDbTbNFdast7FE3XaziHc4A3tEeJ2v 4k0l0uJ62DIWYV6leEFfuVdHpTy4Qve8lnDjfztTN81wDzGErapWSLrgJ vCNHNrWjwSzqm6Y0srA3yHPG3uhinq8fiDNQjz9TwmJyzTBGL23P6r6MO 8=; X-IronPort-AV: E=Sophos;i="5.93,275,1654560000"; d="scan'208";a="124960433" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-pdx-2c-4213ea4c.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-80006.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Aug 2022 19:22:15 +0000 Received: from EX13MTAUWB001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan3.pdx.amazon.com [10.236.137.198]) by email-inbound-relay-pdx-2c-4213ea4c.us-west-2.amazon.com (Postfix) with ESMTPS id 7544B81573; Tue, 30 Aug 2022 19:22:14 +0000 (UTC) Received: from EX19D013UWB001.ant.amazon.com (10.13.138.52) by EX13MTAUWB001.ant.amazon.com (10.43.161.249) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Tue, 30 Aug 2022 19:22:14 +0000 Received: from EX13MTAUWB001.ant.amazon.com (10.43.161.207) by EX19D013UWB001.ant.amazon.com (10.13.138.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1118.12; Tue, 30 Aug 2022 19:22:13 +0000 Received: from dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (172.19.116.181) by mail-relay.amazon.com (10.43.161.249) with Microsoft SMTP Server id 15.0.1497.38 via Frontend Transport; Tue, 30 Aug 2022 19:22:13 +0000 Received: by dev-dsk-farbere-1a-46ecabed.eu-west-1.amazon.com (Postfix, from userid 14301484) id 6024C4D39; Tue, 30 Aug 2022 19:22:12 +0000 (UTC) From: Eliav Farber To: , , , , , , , CC: , , , , , , , , , , , , , Subject: [PATCH v3 12/19] hwmon: (mr75203) fix voltage equation for negative source input Date: Tue, 30 Aug 2022 19:22:05 +0000 Message-ID: <20220830192212.28570-13-farbere@amazon.com> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220830192212.28570-1-farbere@amazon.com> References: <20220830192212.28570-1-farbere@amazon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org According to Moortec Embedded Voltage Monitor (MEVM) series 3 data sheet, the minimum input signal is -100mv and maximum input signal is +1000mv. When n was small enough, such that PVT_N_CONST * n < PVT_R_CONST it resulted in n overflowing to a very large number (since n is u32 type). This change fixes the problem by casting n to long and replacing shift right with div operation. Signed-off-by: Eliav Farber --- V3 -> V2: - Fix equation to support negative values instead of limiting value to zero. drivers/hwmon/mr75203.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c index 1cd5ff6eacce..d1f090a9baac 100644 --- a/drivers/hwmon/mr75203.c +++ b/drivers/hwmon/mr75203.c @@ -222,10 +222,11 @@ static int pvt_read_in(struct device *dev, u32 attr, int channel, long *val) return ret; n &= SAMPLE_DATA_MSK; + /* Convert the N bitstream count into voltage */ pre_scaler = pvt->vd[channel].pre_scaler; - *val = pre_scaler * (PVT_N_CONST * n - PVT_R_CONST) >> - PVT_CONV_BITS; + *val = pre_scaler * (PVT_N_CONST * (long)n - PVT_R_CONST) / + (1 << PVT_CONV_BITS); return 0; default: -- 2.37.1