From patchwork Thu Oct 7 09:57:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleksij Rempel X-Patchwork-Id: 12541487 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1510C433F5 for ; Thu, 7 Oct 2021 09:57:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C94561108 for ; Thu, 7 Oct 2021 09:57:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230467AbhJGJ72 (ORCPT ); Thu, 7 Oct 2021 05:59:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232869AbhJGJ72 (ORCPT ); Thu, 7 Oct 2021 05:59:28 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6FB6C061762 for ; Thu, 7 Oct 2021 02:57:34 -0700 (PDT) Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mYQ9a-0001oY-EZ; Thu, 07 Oct 2021 11:57:30 +0200 Received: from ore by dude.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1mYQ9Z-0007hx-Gq; Thu, 07 Oct 2021 11:57:29 +0200 From: Oleksij Rempel To: Dmitry Torokhov , Eugen Hristev Cc: Oleksij Rempel , kernel@pengutronix.de, linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, David Jander Subject: [PATCH v1] Input: resistive-adc-touch - fix division by zero error on z1 == 0 Date: Thu, 7 Oct 2021 11:57:27 +0200 Message-Id: <20211007095727.29579-1-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-input@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org For proper pressure calculation we need at least x and z1 to be non zero. Even worse, in case z1 we may run in to division by zero error. Fixes: 60b7db914ddd ("Input: resistive-adc-touch - rework mapping of channels") Signed-off-by: Oleksij Rempel --- .../input/touchscreen/resistive-adc-touch.c | 29 ++++++++++--------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/drivers/input/touchscreen/resistive-adc-touch.c b/drivers/input/touchscreen/resistive-adc-touch.c index 744544a723b7..6f754a8d30b1 100644 --- a/drivers/input/touchscreen/resistive-adc-touch.c +++ b/drivers/input/touchscreen/resistive-adc-touch.c @@ -71,19 +71,22 @@ static int grts_cb(const void *data, void *private) unsigned int z2 = touch_info[st->ch_map[GRTS_CH_Z2]]; unsigned int Rt; - Rt = z2; - Rt -= z1; - Rt *= st->x_plate_ohms; - Rt = DIV_ROUND_CLOSEST(Rt, 16); - Rt *= x; - Rt /= z1; - Rt = DIV_ROUND_CLOSEST(Rt, 256); - /* - * On increased pressure the resistance (Rt) is decreasing - * so, convert values to make it looks as real pressure. - */ - if (Rt < GRTS_DEFAULT_PRESSURE_MAX) - press = GRTS_DEFAULT_PRESSURE_MAX - Rt; + if (likely(x && z1)) { + Rt = z2; + Rt -= z1; + Rt *= st->x_plate_ohms; + Rt = DIV_ROUND_CLOSEST(Rt, 16); + Rt *= x; + Rt /= z1; + Rt = DIV_ROUND_CLOSEST(Rt, 256); + /* + * On increased pressure the resistance (Rt) is + * decreasing so, convert values to make it looks as + * real pressure. + */ + if (Rt < GRTS_DEFAULT_PRESSURE_MAX) + press = GRTS_DEFAULT_PRESSURE_MAX - Rt; + } } if ((!x && !y) || (st->pressure && (press < st->pressure_min))) {