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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89BDCC433EF for ; Wed, 13 Oct 2021 09:49:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72E3360F21 for ; Wed, 13 Oct 2021 09:49:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238054AbhJMJu7 (ORCPT ); Wed, 13 Oct 2021 05:50:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40848 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239196AbhJMJuy (ORCPT ); Wed, 13 Oct 2021 05:50:54 -0400 Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA7E3C061570 for ; Wed, 13 Oct 2021 02:48:50 -0700 (PDT) Received: by mail-wr1-x42e.google.com with SMTP id e12so6305008wra.4 for ; Wed, 13 Oct 2021 02:48:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=raspberrypi.com; s=google; h=to:from:subject:message-id:date:user-agent:mime-version :content-language:content-transfer-encoding; bh=Dncr5f630RorEVDAni6of0FL1j48NQFNzLwZhxWYafY=; b=p8QAHCc2IIvGhVBgo/gqFtuNdmy506nFVGu2UvJCY+guPH/kMBTG8mq5kum+Wz29Zo 2krUMb7zVbwYYH/ZmSHQp+u2mCWioFgd5qnSkpRJh1XC2mSD75otaFGkw/JRvr3QqTxW wYyDvoVKrB6P+zdHGbVSI3qu6g0gP9cy/HYK/l/eMAPwIb3uA0jmREa7+PjqoDx9Kj1m iCb45DjHtjc+1qm9fW3NV9G7nER8sEfaLNc5ZTkbJoso+7emtc2NMoGxw2eZ3pTGrDei A3OiYBk3uxQJxO3PmN0WUaH2xRYAnCWUOdvFsNwE6POEIsgoJHe8I5l6drjyTaFB2o7o 4I+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version:content-language:content-transfer-encoding; bh=Dncr5f630RorEVDAni6of0FL1j48NQFNzLwZhxWYafY=; b=l0czJoPZ7pCvoMylUI5eJaPGQlN78iJnzjvOGnyScFmM6KCqH65kasfsZkhvaHXFM2 +DFPFWxWmq4ayJ6ly2M0J+MthISp9m5UuYAHawCw2fsg0N2rLz4JXJkohvUh1O+Czm9v eCjDE2tdwWm54sRWl0qm2bYWYhsPzB022VY4Uq+8Q9iOJXTTDfIS+VY6XgbefpdmD3QS gx/32VQbIzOsPxKT8pvVH6jDlnl5xmecd1GSFgSL+w5WsWQPGF4SX+WmTjySU4QWGFZ4 fEcQKYzWtvtMH3domH4YBRy2AILnnhj40nt+X6NMAmszoihAFDUP2iAs3LGZuLLO6JmH FjwA== X-Gm-Message-State: AOAM530r6uLnZ6AJO2JSk4qZ44ysLnY2heu2U8X7RGaQDwRvm1dWhPgh n38Z52CZveYBn5L255inaSfM8N8/YQssHoqC X-Google-Smtp-Source: ABdhPJxNwhIdNzoEMBV7WPVEg5X1xyxpC6AAnH7tg9RjihGlHaxYUcaKi0S7nEAIJ/8QYWRInD/wjA== X-Received: by 2002:adf:bbc8:: with SMTP id z8mr39614409wrg.281.1634118529214; Wed, 13 Oct 2021 02:48:49 -0700 (PDT) Received: from ?IPv6:2a00:1098:3142:14:b1cf:1ea:46e5:8f4e? ([2a00:1098:3142:14:b1cf:1ea:46e5:8f4e]) by smtp.gmail.com with ESMTPSA id l6sm5244680wmg.10.2021.10.13.02.48.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Oct 2021 02:48:48 -0700 (PDT) To: Alessandro Zummo , Alexandre Belloni , linux-rtc@vger.kernel.org From: Phil Elwell Subject: Question about PCF85063A invalid state Message-ID: <3c6e4252-8271-c968-0bf9-83a23384ce01@raspberrypi.com> Date: Wed, 13 Oct 2021 10:48:48 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org Hi, We're using the PCF85063A on our Compute Module 4 I/O board, and a number of users have experienced problems with invalid state after inserting a backup battery. So far the problem has been confined to EXT_TEST (bit 7 of CTRL_1) being set, but there are a number of registers for which the driver only modifies a subset of the bits. I can think of a number of ways to clear this invalid state, none of which are difficult - force a software reset whenever certain bits of certain registers have certain values, always specifically force some bits to known values, etc. - but are there any preferences or pitfalls to be aware of? Thanks for your input, Phil Elwell, Raspberry Pi