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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 68E93C282CD for ; Mon, 28 Jan 2019 16:51:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 373B12173C for ; Mon, 28 Jan 2019 16:51:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548694301; bh=vNGjbw7LC6HYlUIHZ6diKg8EF6tV4uJg2mI5GdI/Rqc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cfgF+IUv/8QQR8Q32QF+RI0FtKQN0MjTOVfaNrxrhRW8bE81BB9tqyJP0/89KhWaW lMOwL7BfXNLwaSUuScaGRMMfHHgkskNIbDSLinC+b8vMu9h51Q3mbNiRof5huM9iHS fYRt0cem8bC+whcEd6BY19fo5CE5+6EVm1dqVQ8Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388095AbfA1QTV (ORCPT ); Mon, 28 Jan 2019 11:19:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:53868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388566AbfA1QTR (ORCPT ); Mon, 28 Jan 2019 11:19:17 -0500 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 CEB4A2171F; Mon, 28 Jan 2019 16:19:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548692357; bh=vNGjbw7LC6HYlUIHZ6diKg8EF6tV4uJg2mI5GdI/Rqc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vD+l5Rf/FubeismY4UQg9x/kJV5PUHUn6KqIsAnmZ2oivLi7bH/sZBgkZUScaqNyd iAOBdP7D0KgCBOD3+YFnSupuo47RiyJ445siTIu5RJ+/O/PyM6a4f7cZB/Stg6eUp4 fQspQbqGT8Uio2BrMx9cK+/442d5JCrJmbvIwuU8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Bjorn Andersson , Laxman Dewangan , Eduardo Valentin , Sasha Levin , linux-pm@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 162/170] thermal: generic-adc: Fix adc to temp interpolation Date: Mon, 28 Jan 2019 11:11:52 -0500 Message-Id: <20190128161200.55107-162-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190128161200.55107-1-sashal@kernel.org> References: <20190128161200.55107-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Bjorn Andersson [ Upstream commit 9d216211fded20fff301d0317af3238d8383634c ] First correct the edge case to return the last element if we're outside the range, rather than at the last element, so that interpolation is not omitted for points between the two last entries in the table. Then correct the formula to perform linear interpolation based the two points surrounding the read ADC value. The indices for temp are kept as "hi" and "lo" to pair with the adc indices, but there's no requirement that the temperature is provided in descendent order. mult_frac() is used to prevent issues with overflowing the int. Cc: Laxman Dewangan Signed-off-by: Bjorn Andersson Signed-off-by: Eduardo Valentin Signed-off-by: Sasha Levin --- drivers/thermal/thermal-generic-adc.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c index 73f55d6a1721..ad601e5b4175 100644 --- a/drivers/thermal/thermal-generic-adc.c +++ b/drivers/thermal/thermal-generic-adc.c @@ -26,7 +26,7 @@ struct gadc_thermal_info { static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val) { - int temp, adc_hi, adc_lo; + int temp, temp_hi, temp_lo, adc_hi, adc_lo; int i; for (i = 0; i < gti->nlookup_table; i++) { @@ -36,13 +36,17 @@ static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val) if (i == 0) { temp = gti->lookup_table[0]; - } else if (i >= (gti->nlookup_table - 1)) { + } else if (i >= gti->nlookup_table) { temp = gti->lookup_table[2 * (gti->nlookup_table - 1)]; } else { adc_hi = gti->lookup_table[2 * i - 1]; adc_lo = gti->lookup_table[2 * i + 1]; - temp = gti->lookup_table[2 * i]; - temp -= ((val - adc_lo) * 1000) / (adc_hi - adc_lo); + + temp_hi = gti->lookup_table[2 * i - 2]; + temp_lo = gti->lookup_table[2 * i]; + + temp = temp_hi + mult_frac(temp_lo - temp_hi, val - adc_hi, + adc_lo - adc_hi); } return temp; -- 2.19.1