From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793365751; b=v2soFIEhUG4zSQRjbHZZBbAfBPGnQUugOon5XuL6jtWTtHhHPhweMKgmprwlzEvkgn94 e+KTaVbdatsbKehd8dGNVpSjuZi3DUTLV06VcOSs+bbq9VbbJ/5CBdhmw5o+8yGT+2gzQ 43wUaL5XRFGUQYOwbtlZDNTq0J/PKHxvC75OsLw8GZz/AmWfAOv2qMUAlTmcCWc1vhCI2 diRUd2AX/KYNttMMqWFiH0Erhe5Xkd0+r/3wgOKFF3GI2BI/HWxZ2V1tlE0r+gOo3ovrJ rD4kXD94nKj+I8j/0j/WO5nuilgaO2klDZzbR+2XJEgQyLMGI1itIL6u/JBvyF6lt7g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793365751; h=Received:DKIM-Signature:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:Content-Language:Autocrypt:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=HYloytuBxu4sE14pidECPuCOdVzFhqn6Nf0eRwLJzzk=; b=LJen5uxvN5hE41nOi6ssKOgvrENJ+Apwwj1CcDmdblVKAXpd2fKXdAkVGy6D1YROS1Wt haHpz2BD91WdP6LKlyi0girtZq5+CuVBS5pyTYRbi/KzR/9T5VXd+4cJum9KKPXwbDP3D qiyGoyx7MYGnVpXj39OfMlchxICCfncdLlIuAP62n50zP0eLuXVFt636uJ5UPQ+aXVxRA KSsEk1RmGMOzkUrzQzbt7SPgecbJB7vWrPByZxPdZpHJMfxY8kwGZB8GOiQt2ZMFERgPO HyJpOHcsMHkvJCECFx9MufSkM746IlzFX9DMgsU3Dczpb3NPsw+OG0Is1VCgSZQwQTQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OVTWGiGZ; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5DE75606A31C for ; Fri, 30 Oct 2026 13:09:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OVTWGiGZ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D3411F00A1A; Fri, 30 Oct 2026 13:09:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793365751; bh=HYloytuBxu4sE14pidECPuCOdVzFhqn6Nf0eRwLJzzk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=OVTWGiGZ8EAd/uuahVtwVqOMOeRibqKX5kYBYjf8r4J4xvZLtE0JZ8bRzVBE4+xoC iFSGiUBT9avKrsDV5AW356xVn8o2e4VXQZNrdABxPqAsecRgCBXbRAWPshW42whwhW o7Tt1tL2NwxQbWSvVi1gWUo3F2QPtp0KU1nPXBeqsM68ZO6MSlRtCw0kVuM6V2Sy3p ZQmD1pKirFpJ+iZS2OfnkMKnYE2KLlXaWrnIL5wCqD/ltoa8ErsIUYAcLJLXnnVvsx LoR0CvQzuRTkjMhmmqEqJ6W/bXdCvOiJDPbTqk9z8lNj8c1nxMaJd1fesuOzKJmNns hOwjV1EoN44+w== Message-ID: <827abae1-efdb-4e8a-bcb1-233ff418529d@kernel.org> Date: Fri, 30 Oct 2026 14:09:06 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/9] w1: ds2482: set the strong pull-up with its byte To: Greg Kroah-Hartman Cc: Josef Bacik , linux-kernel@vger.kernel.org, stable References: <20261027-llm-char-misc-w1-v1-0-d2e6bfafb6a4@linuxfoundation.org> <20261027-llm-char-misc-w1-v1-3-d2e6bfafb6a4@linuxfoundation.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; keydata= xsFNBFVDQq4BEAC6KeLOfFsAvFMBsrCrJ2bCalhPv5+KQF2PS2+iwZI8BpRZoV+Bd5kWvN79 cFgcqTTuNHjAvxtUG8pQgGTHAObYs6xeYJtjUH0ZX6ndJ33FJYf5V3yXqqjcZ30FgHzJCFUu JMp7PSyMPzpUXfU12yfcRYVEMQrmplNZssmYhiTeVicuOOypWugZKVLGNm0IweVCaZ/DJDIH gNbpvVwjcKYrx85m9cBVEBUGaQP6AT7qlVCkrf50v8bofSIyVa2xmubbAwwFA1oxoOusjPIE J3iadrwpFvsZjF5uHAKS+7wHLoW9hVzOnLbX6ajk5Hf8Pb1m+VH/E8bPBNNYKkfTtypTDUCj NYcd27tjnXfG+SDs/EXNUAIRefCyvaRG7oRYF3Ec+2RgQDRnmmjCjoQNbFrJvJkFHlPeHaeS BosGY+XWKydnmsfY7SSnjAzLUGAFhLd/XDVpb1Een2XucPpKvt9ORF+48gy12FA5GduRLhQU vK4tU7ojoem/G23PcowM1CwPurC8sAVsQb9KmwTGh7rVz3ks3w/zfGBy3+WmLg++C2Wct6nM Pd8/6CBVjEWqD06/RjI2AnjIq5fSEH/BIfXXfC68nMp9BZoy3So4ZsbOlBmtAPvMYX6U8VwD TNeBxJu5Ex0Izf1NV9CzC3nNaFUYOY8KfN01X5SExAoVTr09ewARAQABzSVLcnp5c3p0b2Yg S296bG93c2tpIDxrcnprQGtlcm5lbC5vcmc+wsGPBBMBCgA5AhsDBgsJCAcDAgYVCAIJCgsE FgIDAQIeAQIXgBYhBJvQfg4MUfjVlne3VBuTQ307QWKbBQJp2mE8AAoJEBuTQ307QWKbeaIP /ihHTkTW4KsN/DQ945JJbyu5tI0J80Wue7QyyLPglyKfhgb5cLLNPpOC8cCIJsc7+W3i2P38 s2c1cOH6CYGE7E9ur3Vfme8NW2S2I/Z8VC7bZnzyS23wT17LrsdS/qCpx4o8U+pt/xdXDKph EGRYrIEmMpUWvyYzyYKGIe25FtaayIIKpq8eZYyFcp2f/sG5IkOW5uZzHPMPdcm87jU7fyuQ rAU2vx9r+ulUfQ/q9Z2roC/ode3l7t2pN7BCBCsUDp6JCrUyZrtT1e7EbA0ZRP3aOBNk2P2E DQOgJGjGdO5Yx2Y9LFtltu6JbsBJHi1syGRX3AtQYOMc4Y1WGoeZJmMlvKj2ZqqXNkcWi2DS IQEWB0uW6CqFsBBIMGDa+6OzdaVO/uAVXWDWml02Men3CILdI1MbVjoh8ECqYUY7OQ+JJvNN vnliuq5WM3Ghd3jg/LZZrxXjdIginRHFQCjIJYLKpLZWm1/iDFedcfzqRNYmTtqscdCNHW41 oT3Z7BmO9xwdjuwBS6nmS6JJwkbf5Ot2QR4pB/DRU7ZwjT1qHe+9r9gF32wXVQatHNGK/VVu sfwOnkdxCWkp/qb2gdQRmZh+SedStWshigH6sNfuHBloF/q+hjMRc8b2m326OZdrbSHwY1Sz vti8Hn7n8NjdHO9LKB7BIdjkA9DA5WsqOuVCzsFNBFVDXDQBEADNkrQYSREUL4D3Gws46JEo Z9HEQOKtkrwjrzlw/tCmqVzERRPvz2Xg8n7+HRCrgqnodIYoUh5WsU84N03KlLueMNsWLJBv BaubYN4JuJIdRr4dS4oyF1/fQAQPHh8Thpiz0SAZFx6iWKB7Qrz3OrGCjTPcW6eiOMheesVS 5hxietSmlin+SilmIAPZHx7n242u6kdHOh+/SyLImKn/dh9RzatVpUKbv34eP1wAGldWsRxb f3WP9pFNObSzI/Bo3kA89Xx2rO2roC+Gq4LeHvo7ptzcLcrqaHUAcZ3CgFG88CnA6z6lBZn0 WyewEcPOPdcUB2Q7D/NiUY+HDiV99rAYPJztjeTrBSTnHeSBPb+qn5ZZGQwIdUW9YegxWKvX XHTwB5eMzo/RB6vffwqcnHDoe0q7VgzRRZJwpi6aMIXLfeWZ5Wrwaw2zldFuO4Dt91pFzBSO IpeMtfgb/Pfe/a1WJ/GgaIRIBE+NUqckM+3zJHGmVPqJP/h2Iwv6nw8U+7Yyl6gUBLHFTg2h YnLFJI4Xjg+AX1hHFVKmvl3VBHIsBv0oDcsQWXqY+NaFahT0lRPjYtrTa1v3tem/JoFzZ4B0 p27K+qQCF2R96hVvuEyjzBmdq2esyE6zIqftdo4MOJho8uctOiWbwNNq2U9pPWmu4vXVFBYI GmpyNPYzRm0QPwARAQABwsF2BBgBCgAgAhsMFiEEm9B+DgxR+NWWd7dUG5NDfTtBYpsFAmna YUkACgkQG5NDfTtBYptX+BAApg32CkxwNucNEi8WfWA8oKkW0y8YDuY6ORMo9FWNGiT/OTy0 vyJrLocrpn86zwfjVp+eCrssPYh8eqJfnWqmYv6ACQtHPYzPZQ3mSo8H97Z01oUxITzCxpXm ZkLgPIqtDPcC2E3dPM/fVxcyowM8XsaMA9wcsaUYrta8toOq2b9tKcjleKMfMrm0gQ9u7wUc QbLkwj6TCLOwucb07GXzLTNF9PZmaDUpKAZjMjmrW+le+SFvQbhamx0rxLWPR0NWntXpbCn+ +ACch03p/JyTBVktxFsFyCt7pTPE1kEaeuXBTe/a2D9iQvRxRW19LvuO2e59/u1wYUiH/orz wbIC2S4dBsPAPihL3ztOU1yE86GPyQtSE0kU+/7snnLt4QGi6PChf3t5gnNjAzjUUovO8rgI c+5yN5heq5loYHgK6OQ9OlHzsPHO9e9MOQcKlFycs1pyijFGzDwdNUm/SchK8iWT2QApTx4A K9bCVaboTA2T77QYkRcRJYSsO1alGX0ome/hMLD1daXlkrNUp1HWa3K4iytLRXjCSIorWiGs n+q3krnpXu3TFkA8qtOFZMdnIiFuiq1yLT8hptsV5xh1TA2nsVvSYiaCr3q4s4BKjS/KrLDb qoxzw8ISjdUp4pA85vb6YLCmb39NgidD+7PmAr65lBNveIFynTgsja1rRQ4= In-Reply-To: <20261027-llm-char-misc-w1-v1-3-d2e6bfafb6a4@linuxfoundation.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/10/2026 17:04, Greg Kroah-Hartman wrote: > From: Josef Bacik > > The eight channels of a DS2482-800 are eight independent 1-wire masters > for the w1 core, but share one I2C device. Each bus operation consists of > several I2C transfers: select the channel, send the command, poll the > status, set the read pointer, read the result. access_lock keeps the > operations of the channels apart. > > ds2482_w1_set_pullup() polls the status, writes the configuration and > polls again without the lock. Polling sets the read pointer of the device > to the status register. In the middle of a read on another channel, after > that one has set the pointer to the data register, this makes the read > return the status instead of the data. The cached copy of the pointer in > pdev->read_prt can go wrong as well. > > The lock alone is not enough. The strong pull-up is a setting of the > whole chip which is used up by the next byte. If an operation of another > channel gets in before the byte it was meant for, that channel gets the > pull-up, and the sensor converts without power. > > So only note the request in ds2482_w1_set_pullup(), and write the > configuration in ds2482_w1_write_byte(), under the lock and after the > channel has been selected. The w1 core calls the former right before the > latter, under the bus mutex of the channel. > > Fixes: 9c95bb6f25ff ("w1: ds2482: Added 1-Wire pull-up support to the driver") > Cc: stable > Signed-off-by: Josef Bacik > Signed-off-by: Greg Kroah-Hartman Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof