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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 63FFAC43331 for ; Mon, 11 Nov 2019 18:36:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A5742184C for ; Mon, 11 Nov 2019 18:36:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573497367; bh=xs/uc3tSF9YOdmddui/dzZ64YJC7ZTdzZFgbGi7P0Yc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=poEXCDfcE7VIUz+RM6HfR89wo4aWSYXZ30QtdKhaYLfFxb+bRb6IHwsQUbPUdvo0V T8gPLW6oFygeBqo7HWlItawkg0T4z4m/6cwwBBf1vaI+4IfQpmnyT5uN7JxZFrxitx hZ10gMyg8HrDytC+U7JVENYwz0Jr67+ez/x8FbaQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728668AbfKKSgF (ORCPT ); Mon, 11 Nov 2019 13:36:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:54148 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727515AbfKKSgD (ORCPT ); Mon, 11 Nov 2019 13:36:03 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3757221655; Mon, 11 Nov 2019 18:36:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573497362; bh=xs/uc3tSF9YOdmddui/dzZ64YJC7ZTdzZFgbGi7P0Yc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V/FXrQPkQvC/orwkKmBUzqBcDWJHXeIgPTyQrcLkNrpLyFt191G1rGCOjaPMI6Wrs 5ptJs8Nlana/H0xp0TN+c/9uv62JTnEVHzSQDEtRYwkq0qcxQwSjokF/W59ynSMD45 jen1fmxlw/5uyAVwYCHekeI7cjPUFNZ56IHwBZeA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Zbyn=C4=9Bk=20Kocur?= , Andreas Klinger , Stable@vger.kernel.org, Jonathan Cameron Subject: [PATCH 4.14 028/105] iio: srf04: fix wrong limitation in distance measuring Date: Mon, 11 Nov 2019 19:27:58 +0100 Message-Id: <20191111181437.842601796@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191111181421.390326245@linuxfoundation.org> References: <20191111181421.390326245@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andreas Klinger commit 431f7667bd6889a274913162dfd19cce9d84848e upstream. The measured time value in the driver is limited to the maximum distance which can be read by the sensor. This limitation was wrong and is fixed by this patch. It also takes into account that we are supporting a variety of sensors today and that the recently added sensors have a higher maximum distance range. Changes in v2: - Added a Tested-by Suggested-by: Zbyněk Kocur Tested-by: Zbyněk Kocur Signed-off-by: Andreas Klinger Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/proximity/srf04.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) --- a/drivers/iio/proximity/srf04.c +++ b/drivers/iio/proximity/srf04.c @@ -105,7 +105,7 @@ static int srf04_read(struct srf04_data udelay(10); gpiod_set_value(data->gpiod_trig, 0); - /* it cannot take more than 20 ms */ + /* it should not take more than 20 ms until echo is rising */ ret = wait_for_completion_killable_timeout(&data->rising, HZ/50); if (ret < 0) { mutex_unlock(&data->lock); @@ -115,7 +115,8 @@ static int srf04_read(struct srf04_data return -ETIMEDOUT; } - ret = wait_for_completion_killable_timeout(&data->falling, HZ/50); + /* it cannot take more than 50 ms until echo is falling */ + ret = wait_for_completion_killable_timeout(&data->falling, HZ/20); if (ret < 0) { mutex_unlock(&data->lock); return ret; @@ -130,19 +131,19 @@ static int srf04_read(struct srf04_data dt_ns = ktime_to_ns(ktime_dt); /* - * measuring more than 3 meters is beyond the capabilities of - * the sensor + * measuring more than 6,45 meters is beyond the capabilities of + * the supported sensors * ==> filter out invalid results for not measuring echos of * another us sensor * * formula: - * distance 3 m - * time = ---------- = --------- = 9404389 ns - * speed 319 m/s + * distance 6,45 * 2 m + * time = ---------- = ------------ = 40438871 ns + * speed 319 m/s * * using a minimum speed at -20 °C of 319 m/s */ - if (dt_ns > 9404389) + if (dt_ns > 40438871) return -EIO; time_ns = dt_ns; @@ -154,20 +155,20 @@ static int srf04_read(struct srf04_data * with Temp in °C * and speed in m/s * - * use 343 m/s as ultrasonic speed at 20 °C here in absence of the + * use 343,5 m/s as ultrasonic speed at 20 °C here in absence of the * temperature * * therefore: - * time 343 - * distance = ------ * ----- - * 10^6 2 + * time 343,5 time * 106 + * distance = ------ * ------- = ------------ + * 10^6 2 617176 * with time in ns * and distance in mm (one way) * - * because we limit to 3 meters the multiplication with 343 just + * because we limit to 6,45 meters the multiplication with 106 just * fits into 32 bit */ - distance_mm = time_ns * 343 / 2000000; + distance_mm = time_ns * 106 / 617176; return distance_mm; }