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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D770C3A59E for ; Wed, 21 Aug 2019 06:27:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1094122DA7 for ; Wed, 21 Aug 2019 06:27:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726484AbfHUG1T (ORCPT ); Wed, 21 Aug 2019 02:27:19 -0400 Received: from hel-mailgw-01.vaisala.com ([193.143.230.17]:8486 "EHLO hel-mailgw-01.vaisala.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbfHUG1T (ORCPT ); Wed, 21 Aug 2019 02:27:19 -0400 X-Greylist: delayed 427 seconds by postgrey-1.27 at vger.kernel.org; Wed, 21 Aug 2019 02:27:17 EDT IronPort-SDR: 8V8EhrJCUuKyTElVrk+Etk8MRSkN3jFaTOcIXL2ySLd8T/kMnYbJLkp4/a8ZXluS2r5ezUsoIn pibmHCVYXvHmMawGPM2NQzs/dHbFEI8ifb0RsvzGfuPfSsMPVmJkV8u16ce9v9Zn5yCPQC/0a+ nJ+/azIRxQUt+8Y+piWZwPFJqeftIelZfP/+/8z1/zIjv5A8DQH8x1ctAzyj+90SvlKWb4xOx8 hckWud2MNG3/cWzrgIV1HaAWIgZp8ELvdgD9u6ArUaOTUp6Un1SisPWpV2bzjc47TRFT2052uN DhU= X-IronPort-AV: E=Sophos;i="5.64,411,1559509200"; d="scan'208";a="229121716" Subject: Re: [v2] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w To: Li Yang , Alexandre Belloni , Mark Brown Cc: Biwen Li , a.zummo@towertech.it, linux-rtc@vger.kernel.org, lkml References: <20190816024636.34738-1-biwen.li@nxp.com> <20190816080417.GB3545@piout.net> <20190816162825.GE3545@piout.net> From: Nandor Han Message-ID: Date: Wed, 21 Aug 2019 09:20:05 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 21 Aug 2019 06:20:05.0337 (UTC) FILETIME=[791E8490:01D557E8] Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org On 8/16/19 10:40 PM, Li Yang wrote: > On Fri, Aug 16, 2019 at 11:30 AM Alexandre Belloni > wrote: >> >> On 16/08/2019 10:50:49-0500, Li Yang wrote: >>> On Fri, Aug 16, 2019 at 3:05 AM Alexandre Belloni >>> wrote: >>>> >>>> On 16/08/2019 10:46:36+0800, Biwen Li wrote: >>>>> Issue: >>>>> - # hwclock -w >>>>> hwclock: RTC_SET_TIME: Invalid argument >>>>> >>>>> Why: >>>>> - Relative patch: https://lkml.org/lkml/2019/4/3/55 , this patch >>>>> will always check for unwritable registers, it will compare reg >>>>> with max_register in regmap_writeable. >>>>> >>>>> - In drivers/rtc/rtc-pcf85363.c, CTRL_STOP_EN is 0x2e, but DT_100THS >>>>> is 0, max_regiter is 0x2f, then reg will be equal to 0x30, >>>>> '0x30 < 0x2f' is false,so regmap_writeable will return false. >>>>> >>>>> - Root cause: the buf[] was written to a wrong place in the file >>>>> drivers/rtc/rtc-pcf85363.c >>>>> >>>> >>>> This is not true, the RTC wraps the register accesses properly and this >>> >>> This performance hack probably deserve some explanation in the code comment. :) >>> >>>> is probably something that should be handled by regmap_writable. >>> >>> The address wrapping is specific to this RTC chip. Is it also >>> commonly used by other I2C devices? I'm not sure if regmap_writable >>> should handle the wrapping case if it is too special. >>> >> >> Most of the i2c RTCs do address wrapping which is sometimes the only way >> to properly set the time. > > Adding Mark and Nandor to the loop. > > Regards, > Leo > Hi, `regmap` provides couple of ways to validate the registers: max_register, callback function and write table. All of these are optional, so it gives you the freedom to customize it as needed. In this situation probably you could: 1. Avoid using the wrapping feature of pcf85363 (you can just provide separate calls for stop, reset and time confguration). In this way the `max_register` validation method will work fine. 2. Replace `max_register` method validation with `callback function` validation method, were you could make your own validation. Regards, Nandor