From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f50.google.com (mail-oo1-f50.google.com [209.85.161.50]) (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 034D2376E6; Wed, 12 Jun 2024 05:06:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718168804; cv=none; b=nvgh0zRHrhs5Id2Q7df4s8eHa5O8umrTO2mGUBW+YlMM9NUzX169iwhvhFUXg5hq0x2Slf6F4qGJzq59UdSDmEj/mvWbFGqZR0q48KFCmPnENPJKmVxpvMQ7nHIZlOeFsewka6Gkh0X8EGHqmDgg+iulAo8BUVf44pFK5hV0qtA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718168804; c=relaxed/simple; bh=CXtcUMWwJkEIqpnRMKcKS4gCggMkOvjE0n81czXvH1g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lBY7jf0HiNQFerSdsLAC8xzfRBIHhHvB8jUJIXfvBp98zvdDxW6fVXTj5oXQhzDHF+hBNGMd6H86HN0CPUhsdCQpsee7wTAsxoVgbCdFkNOJn1jR7H70pFECtvRX8TUWvaraRsyGYP6Z6J+Rk5HayQV5P5ZQ53JtNM3/SsY3cO8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=C8NhMmNj; arc=none smtp.client-ip=209.85.161.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com 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="C8NhMmNj" Received: by mail-oo1-f50.google.com with SMTP id 006d021491bc7-5bb10cfe7daso231244eaf.2; Tue, 11 Jun 2024 22:06:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1718168802; x=1718773602; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=3dXYS15oeWjHskZX8YaOnpu7b/X3OJH0Z2xci2rbkY4=; b=C8NhMmNjmI4/N3t94ZQsE/WYakCdRiul4Fbm3KbGOf1DkrOAuCyX7XBd7X0NLpdozu N83/haWA8sQu37duWihntw6Er0gGDXGMZxXxbqpLH48qXqqm0jlnXkyhVYpK460f0oZT NJF7rFBmbALEPvGEMvt6A1vphy8nONgvBvHvqGwOdP3m/aDYz2LJx1RXdsDcAn3Kg/2E HX/DmsbiEtBFOYm5o0IF24Bcl0az+D3CVasrtrjpLtuidVslS9PrXpTAltdZbZ0nSWHy TBE4MYlbG07zcdZqCj0L4tSakcR1KB+egW++U70YQOjTuscHP+OuhEifHTf32Q6hqIAJ KsxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718168802; x=1718773602; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=3dXYS15oeWjHskZX8YaOnpu7b/X3OJH0Z2xci2rbkY4=; b=Xg8v0IWGe2dQSGQ6rnJy6+et7fNvQt0MaMs8ao/wz+9BW3sVYFn5QMcCJgpjQym/5R A33cUT5aTu7nSt+OYwRXvA9Ng3u3WUi6lT2XgNM+KZdRGG10nMpCqYT7KGeNse5opGWw eZHJq7lzTdA9jNlE97fCcvKn1qWMEqO6iF0CKrYnbgNoj9nmAU6g0P9cKcaEGbzsh7zB D9KZvMXZIWr1VSUNQPVjLSxQH8DDBBE9iwOokrBprRJ5l1rnYroQI+ZURU1SpJ2osxIR +JiLLmIqujzw4E6pOLs6oVBmCxQR+n5PzSlerZQCWjy89ZcP/FFjRlPZFNMWi2alA+8K t1XQ== X-Forwarded-Encrypted: i=1; AJvYcCWPn3/A/zLbFtNFjchQk18pW+8L0RRWior28iu9BUaq2z3SyM4DKIO5NjEYoAF5+54Aqaf5fKiPlLySCsd6hSZBhe4tmr9ddGX4DEoN X-Gm-Message-State: AOJu0Yx6dyIGxI+14w26NgaGzNebXEaaFjobL5pG35xac9QiDW6kbP1f MEtOloGcv7In+N4I+eAOWE+L1NlwzDYk2iIBn5JSljnCIpFU3Cw7 X-Google-Smtp-Source: AGHT+IEgHkA1mSW5y3Jnsg39tt8JnGXbUkGlJIsltSfOEkfg4Nvkb9kRlwfnjq2i674ZZeRgJ2xYnQ== X-Received: by 2002:a4a:8552:0:b0:5ba:ca86:a025 with SMTP id 006d021491bc7-5bb3b7a9135mr944467eaf.0.1718168801852; Tue, 11 Jun 2024 22:06:41 -0700 (PDT) Received: from hoboy.vegasvil.org ([2600:1700:2430:6f6f:e2d5:5eff:fea5:802f]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5bac95e0733sm1621549eaf.7.2024.06.11.22.06.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Jun 2024 22:06:41 -0700 (PDT) Date: Tue, 11 Jun 2024 22:06:39 -0700 From: Richard Cochran To: =?iso-8859-1?B?Q3Pza+FzLA==?= Bence Cc: linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org, =?iso-8859-1?Q?Szentendrei=2C_Tam=E1s?= , Alexandre Belloni , Miroslav Lichvar Subject: Re: [RFC PATCH v2] rtc: pcf2127: Add PPS capability through Seconds Interrupt Message-ID: References: <20240611150458.684349-1-csokas.bence@prolan.hu> Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240611150458.684349-1-csokas.bence@prolan.hu> (adding Miroslav onto CC) On Tue, Jun 11, 2024 at 05:04:57PM +0200, Csókás, Bence wrote: > PCF2127/29/31 is capable of generating an interrupt on every > second (SI) or minute (MI) change. It signals this through > the Minute/Second Flag (MSF) as well, which needs to be cleared. This is a RFC, and my comment is that a PPS from an RTC is not useful to the Linux kernel. The kernel only uses the RTC to boot strap the wall clock to some approximate phase. After that, Linux either continues with a free running clock, or it synchronizes to a global time source via NTP. In the latter case, Linux will write the NTP time back into the RTC. So I can't see how the RTC's PPS provides any benefit. Thanks, Richard