From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f169.google.com (mail-pg1-f169.google.com [209.85.215.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E0D8C1D5AB5; Mon, 12 May 2025 13:53:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747058005; cv=none; b=ZCRT6X6ZdTDf/FDhzhq9ndnVMyhDDfVKzLtFkoSNB0rwWXdS1Q+a6+gYCNSORyCoX2sZIbUP9LjMo7XNuY/MWBrh7KpwMk3iJmj8RjClR+MqRVjB/76I2XdE754HOteK9ukIgaNq7RM0LUE+JFFB7kFKaLztX3puvXsMHGuAnb8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747058005; c=relaxed/simple; bh=lvsYJSXqb60BAPqXPM1u1J9tq4X1c4s6rvU2ztnDsd4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Z9Scy/W7rxNr7HeTnIISy82tbtnGAs5Mh8fzKVa+UB2RFDo9IUq3axMDeEn5QKJhQFsHTR7mFgvi/lvnBj4SOownq8vKWTB62QzFQ8krJ272bg9qzbATZNjH5clBTLSeXhag7AEKVWTHE6Rz4YYDEKQqLxQzHSa/GMK6tYsWVGM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=hHDV/5qx; arc=none smtp.client-ip=209.85.215.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hHDV/5qx" Received: by mail-pg1-f169.google.com with SMTP id 41be03b00d2f7-b13e0471a2dso3072433a12.2; Mon, 12 May 2025 06:53:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1747058003; x=1747662803; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:sender:from:to:cc:subject:date:message-id:reply-to; bh=cnmwp28GVHdo2cvf2bRtl0sYQfkO+XMPcFATxv9hQkM=; b=hHDV/5qxJL5rmptT33hSJu/f0B22lrCRxi6tSRYWLQqXrAp2d0HWQr+4rboa8g9clJ ZsaoRPBGQCPQ/ymgLgp+ZAfRdsUCFFy6oXQTR9dcsEvSrXgT5Y89b78pk3oaXdsIr7Iu zAi8n4+/fpG5WoUBoF1tK85J96666sH2ewMnIps1fSLYFVfOt+Esaw1czbRKOytW0EFB j+C67ajAQ+JqEVhpeznxZDPbY5Gz5zBhtIvocr+BYcyBiiZkoyLiOyKI8Bk7edaP+fSm YlEN9toCJqGWLA+ZlnMgUaQOZHWXjqSDGCJwncZHUuggUQuOB+ggYy/NRuZlLRg9bmIp uwBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747058003; x=1747662803; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:sender:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cnmwp28GVHdo2cvf2bRtl0sYQfkO+XMPcFATxv9hQkM=; b=Ec2tax9Zu6pOTficukIlXRJ+zKjXsK0gdm/U+i5ky4uGmXD6UN9ov6cnpCb9d6ysVw nX31vXrEx0RMiYVFut18cE2/O9v6/OiZmii1X5DmoGTdU/MgVHtrTEzUG+XOifTpFPph XEvOv9DNcovr+AT40Q51PqBHXwiqFSTayevb46LK3pSze9G6ZVta02ZS/o1zZEGU0/6r +dCtaCozBvCvRPoKzj0gJIsQ3s/kt946KYfuFZQEj4aetAWWnBxRF2Xz8K94ltiyzXMc yTg1EVlbJ5Bq12GnWpiPIMPCI+CulWE7eCF1XBzkzSfNubAjyhr/5TqUfRrkeo0OOOjH mhqQ== X-Forwarded-Encrypted: i=1; AJvYcCUsfjjwQuRk15u5mjM3oQ5aKU7y9ZDP5bStFPL+3zxKRhzXrZb0fdy2agbmazUKi66C9EwKjnd/8MkCgI3W@vger.kernel.org, AJvYcCVJxsVG3d4Jnb02Cr/sUANFhGMcH8e4PHsWoHzysRHJwcwDGLkKC3xOxg0wrL7HWV1nKjNp+4HwGN3H@vger.kernel.org, AJvYcCVsv7d6NjcXvkEbNFcpyPjGQqqHhWkaaLZoaJRWVXUZ5URo/ZtDcAeRh6y6u1Ip7UerkfjN+x9uHfeUwQ==@vger.kernel.org X-Gm-Message-State: AOJu0YwpmLpCG1kcFu+9JDdNjbNiwdwlB4+Zhx8F0L72JjU9BIXtLtdz 5PN0t9hmB/uYZFaBcYi5bj+LFNr5iSJ23kD+ljwmwF2zgnKaCK3ViV/9bA== X-Gm-Gg: ASbGnctvWopvSPwLYfIsDMFAxkkqA0vMDENJw5vZKrtsA7Dk8ZLZFhwI+jcNVYc4NL2 I0o8I4FMYf+7R6Qlgj3BHDlWp2Czzd9gsneZga40eaq0sv5XJlBh62/Oizrzt1Njdb+HeLJ9DRd MpE937XGf7zZ5ZqU0BYiFEb51tw9ZkNO7oEgKVBzemUUJPEmy4emm0KCtUA85Ybo8nETyl/iE+q ZiTneebquSPHjUtp1H3YxAeZb/OqTHyqsdS3WuzvNDsctHRuuU9PO7xInP9w4atr3lsCUXwWIPj sQCPkIMoPfnHu+9hK2dMoH37LgYR66OGm7bUy4udcg9wtULSO0Tr78sS7kdKAaD7b9oLZ9EmP0F AoLX2z2QRzzdqMD+1Vo9PSgHg X-Google-Smtp-Source: AGHT+IHzx07XVe7gqTpQfz5qoZruYP2L5AVH5/tVInM2ZAqDnqexOrsMl0t71UTgXW5i2nWhPdhX/g== X-Received: by 2002:a17:902:f78e:b0:22e:8354:dc8a with SMTP id d9443c01a7336-22fc8e99da3mr197824195ad.37.1747058002993; Mon, 12 May 2025 06:53:22 -0700 (PDT) Received: from ?IPV6:2600:1700:e321:62f0:da43:aeff:fecc:bfd5? ([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22fc82a0d9bsm63217235ad.219.2025.05.12.06.53.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 May 2025 06:53:22 -0700 (PDT) Sender: Guenter Roeck Message-ID: Date: Mon, 12 May 2025 06:53:21 -0700 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] pwm: mc33xs2410: add support for temperature sensors To: Dimitri Fedrau Cc: dimitri.fedrau@liebherr.com, =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Jean Delvare , linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org References: <20250512-mc33xs2410-hwmon-v1-1-addba77c78f9@liebherr.com> <1bd48694-9760-4e6b-9138-4651d42ff032@roeck-us.net> <20250512133114.GA6440@legfed1> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= In-Reply-To: <20250512133114.GA6440@legfed1> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/12/25 06:31, Dimitri Fedrau wrote: > Hi Guenter, > > Am Mon, May 12, 2025 at 06:04:33AM -0700 schrieb Guenter Roeck: >> On 5/12/25 04:26, Dimitri Fedrau via B4 Relay wrote: >>> From: Dimitri Fedrau >>> >>> The MC33XS2410 provides temperature sensors for the central die temperature >>> and the four outputs. Additionally a common temperature warning threshold >>> can be configured for the outputs. Add hwmon support for the sensors. >>> >>> Signed-off-by: Dimitri Fedrau >>> --- >> >>> + >>> +static int mc33xs2410_hwmon_read_out_status(struct spi_device *spi, >>> + int channel, u16 *val) >>> +{ >>> + int ret; >>> + >>> + ret = mc33xs2410_read_reg_diag(spi, MC33XS2410_OUT_STA(channel), val); >>> + if (ret < 0) >>> + return ret; >>> + >>> + /* Bits latches high */ >>> + return mc33xs2410_read_reg_diag(spi, MC33XS2410_OUT_STA(channel), val); >> >> Is that double read of the same register needed ? If so, you'll probably >> need a lock to prevent it from being executed from multiple threads at the >> same time. >> >> The comment "Bit latches high" doesn't really mean anything to me and doesn't >> explain why the register needs to be read twice. >> >> > > All bits of the output status registers are latched high. In case there > was overtemperature detected, the bit stays set until read once and cleared > afterwards. So I need a second read to get the "realtime" status. > Otherwise I might end up returning an false positive overtemperature > warning. I don't think a lock is really necessary, since I'm only > interested in the "realtime" status but not if there was a warning in > the past. What do you think ? > Hardware monitoring is _expected_ to report the last latched status and clear it afterwards, to ensure that historic alarms are reported at least once. This isn't about "false positive", it is about "report at least once if possible". Given that, the second read is unnecessary from hwmon ABI perspective. If you don't want to do that, you should explicitly document that latched (historic) over-temperature alarms are not reported. Guenter