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=-11.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C28D8CA9ECB for ; Thu, 31 Oct 2019 16:44:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96804208C0 for ; Thu, 31 Oct 2019 16:44:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572540266; bh=MuiSMfYiw9dn1Bwi6Oc3CqfBuFOn3aOLlOIMGK7dQGU=; h=Subject:To:From:Date:List-ID:From; b=qMcp10X7PwOVtHkhtLv80/SM4nK5yNexgncMGhaac9ceiL2cZY656e+yAmOzA98yC ZcOc4pKOVc+ErSXEWuidn8S233Rhq7CJRzB8cHyhmlJ7pfwl183UGVPVj6EC+nIWJ8 4Fz7qW0/Uh4BhUHGeJGn6ekjmVCDtFWLpmNcWGVs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728554AbfJaQo0 (ORCPT ); Thu, 31 Oct 2019 12:44:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:37090 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728521AbfJaQo0 (ORCPT ); Thu, 31 Oct 2019 12:44:26 -0400 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 C54A420873; Thu, 31 Oct 2019 16:44:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572540265; bh=MuiSMfYiw9dn1Bwi6Oc3CqfBuFOn3aOLlOIMGK7dQGU=; h=Subject:To:From:Date:From; b=tbCLZtV12dLIqM7et7pq7IX0xjvOh+I5pBzCl/kZIcZ7KYDlbAM6UPCn/DSa5bcGA QbZQFyKMBzNJhZ2zLpSvKqn4zqPjkAvMpa4ryo2SL4De9stFHKrjZTWqX/qY82X0Xz a53a447BMBKla5q6WflC5pVHuLuqHPnRdAuERLJE= Subject: patch "iio: srf04: fix wrong limitation in distance measuring" added to staging-linus To: ak@it-klinger.de, Jonathan.Cameron@huawei.com, Stable@vger.kernel.org, zbynek.kocur@fel.cvut.cz From: Date: Thu, 31 Oct 2019 17:44:14 +0100 Message-ID: <157254025422163@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled iio: srf04: fix wrong limitation in distance measuring to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 431f7667bd6889a274913162dfd19cce9d84848e Mon Sep 17 00:00:00 2001 From: Andreas Klinger Date: Sun, 6 Oct 2019 16:29:56 +0200 Subject: iio: srf04: fix wrong limitation in distance measuring MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- drivers/iio/proximity/srf04.c | 29 +++++++++++++++-------------- 1 file changed, 15 insertions(+), 14 deletions(-) diff --git a/drivers/iio/proximity/srf04.c b/drivers/iio/proximity/srf04.c index 8b50d56b0a03..01eb8cc63076 100644 --- a/drivers/iio/proximity/srf04.c +++ b/drivers/iio/proximity/srf04.c @@ -110,7 +110,7 @@ static int srf04_read(struct srf04_data *data) udelay(data->cfg->trigger_pulse_us); 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); @@ -120,7 +120,8 @@ static int srf04_read(struct srf04_data *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; @@ -135,19 +136,19 @@ static int srf04_read(struct srf04_data *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; @@ -159,20 +160,20 @@ static int srf04_read(struct srf04_data *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; } -- 2.23.0