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 75721C433F5 for ; Sat, 20 Nov 2021 21:08:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235477AbhKTVLU (ORCPT ); Sat, 20 Nov 2021 16:11:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234879AbhKTVLT (ORCPT ); Sat, 20 Nov 2021 16:11:19 -0500 Received: from mail-ot1-x32e.google.com (mail-ot1-x32e.google.com [IPv6:2607:f8b0:4864:20::32e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE41AC061574; Sat, 20 Nov 2021 13:08:15 -0800 (PST) Received: by mail-ot1-x32e.google.com with SMTP id h16-20020a9d7990000000b0055c7ae44dd2so22404886otm.10; Sat, 20 Nov 2021 13:08:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=EGzBIS8YcmZkggi1HZxJDBiWMaVvrZf9iB+lDd3ba20=; b=iNV3Foyh1pATT8jRoBtXQDaL9Id6zaD6t5esFATAn2qW4zzayYBF0wUQkbe0ySVLxd YpoiJaj9z5sLfbpYCFTTWJIfh7Nd72M0DbiVQ3Dm6ZlFpKeY7wR8ZxmxvkLEZpoRB7vL MLRHOA2Abt1JA43FVs/cLjrl5Slt2PqGzIJ3nXTKiIxirdMMkHmVBQ+C1vMKzBsNEMC0 Xn3TSABY7CgQRGIcjxAF7lRLCOSYQQBJUJZ1+HUa+MO56XQFrwsmJ/0L2yA3FmK5pHSm IrR0Vkd7oqA/2/klAL9k1CFw7fK3KvBEDRNQOb2U/l9PKneA/iXFXkV+b5k42IChYTrx 7/rg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=EGzBIS8YcmZkggi1HZxJDBiWMaVvrZf9iB+lDd3ba20=; b=XfcE5qycOWXtDoyKqWbi3T4/YZiiH43UwKvvD7iHfQRwSaL9XPV0SWHi3lHTpzgqNz 3+JHJP6b9wTcFdsbfqd8UdkWU1lwPg5cHHwgMrFHPWKR3btSoTDRhdVbBdafO7KWTdNz csDFhajjPo/oVix94Jy1U6y7R3ZAD7f4CSogZn/T+TVjtXs2woGe4KOS9qK2+Lge54Gp DJJxPaahh1uD50ARqp7xy/eC8eANAjhdjsmBjZ997sabsv077sboO0+BqBRQOGVz7ZvT 7ETM+65uGpmLYoJ+OKnw4wayQLyRCTXyernbvjvpiO7qmvlrUaLJqZAiaRgWvIs3p+nU Ny5A== X-Gm-Message-State: AOAM5300IzBdQ8snk8OVcKo+H8wKd1+HZvxRrYxhXtOIpo8MrVddfbTd HytVF2HGUpGQKvHYk9tbh+alYMJv/mw= X-Google-Smtp-Source: ABdhPJwVaCQTmLtgCGgxYl7gzPMaUuWBz4EDxS7uVyJTRDfU5518V2cbqpUWxJ2fypO+XA7oNkBgqA== X-Received: by 2002:a05:6830:1107:: with SMTP id w7mr13863789otq.20.1637442494846; Sat, 20 Nov 2021 13:08:14 -0800 (PST) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id h6sm748264otb.60.2021.11.20.13.08.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 20 Nov 2021 13:08:14 -0800 (PST) Sender: Guenter Roeck Subject: Re: [PATCH v2 1/2] hwmon: (sht4x) Fix EREMOTEIO errors To: David Mosberger-Tang , Navin Sankar Velliangiri Cc: Jean Delvare , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org References: <20211120204053.2299501-1-davidm@egauge.net> From: Guenter Roeck Message-ID: Date: Sat, 20 Nov 2021 13:08:12 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211120204053.2299501-1-davidm@egauge.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/20/21 12:40 PM, David Mosberger-Tang wrote: > Per datasheet, SHT4x may need up to 8.2ms for a "high repeatability" > measurement to complete. Attempting to read the result too early > triggers a NAK which then causes an EREMOTEIO error. > > This behavior has been confirmed with a logic analyzer while running > the I2C bus at only 40kHz. The low frequency precludes any > signal-integrity issues, which was also confirmed by the absence of > any CRC8 errors. In this configuration, a NAK occurred on any read > that followed the measurement command within less than 8.2ms. > > Signed-off-by: David Mosberger-Tang You sent v2 after 5 minutes, and there is no change log. Please never do that, and always provide a change log. Guenter > --- > drivers/hwmon/sht4x.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwmon/sht4x.c b/drivers/hwmon/sht4x.c > index 09c2a0b06444..3415d7a0e0fc 100644 > --- a/drivers/hwmon/sht4x.c > +++ b/drivers/hwmon/sht4x.c > @@ -23,7 +23,7 @@ > /* > * I2C command delays (in microseconds) > */ > -#define SHT4X_MEAS_DELAY 1000 > +#define SHT4X_MEAS_DELAY_HPM 8200 /* see t_MEAS,h in datasheet */ > #define SHT4X_DELAY_EXTRA 10000 > > /* > @@ -90,7 +90,7 @@ static int sht4x_read_values(struct sht4x_data *data) > if (ret < 0) > goto unlock; > > - usleep_range(SHT4X_MEAS_DELAY, SHT4X_MEAS_DELAY + SHT4X_DELAY_EXTRA); > + usleep_range(SHT4X_MEAS_DELAY_HPM, SHT4X_MEAS_DELAY_HPM + SHT4X_DELAY_EXTRA); > > ret = i2c_master_recv(client, raw_data, SHT4X_RESPONSE_LENGTH); > if (ret != SHT4X_RESPONSE_LENGTH) { >