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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 0E837C43603 for ; Thu, 12 Dec 2019 10:37:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE80A20663 for ; Thu, 12 Dec 2019 10:37:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728715AbfLLKhK (ORCPT ); Thu, 12 Dec 2019 05:37:10 -0500 Received: from relay8-d.mail.gandi.net ([217.70.183.201]:55949 "EHLO relay8-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728679AbfLLKhK (ORCPT ); Thu, 12 Dec 2019 05:37:10 -0500 X-Originating-IP: 93.29.109.196 Received: from localhost.localdomain (196.109.29.93.rev.sfr.net [93.29.109.196]) (Authenticated sender: paul.kocialkowski@bootlin.com) by relay8-d.mail.gandi.net (Postfix) with ESMTPSA id 8955B1BF218; Thu, 12 Dec 2019 10:37:07 +0000 (UTC) From: Paul Kocialkowski To: linux-rtc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Alessandro Zummo , Alexandre Belloni , Thomas Petazzoni , Paul Kocialkowski Subject: [PATCH 1/2] rtc: hym8563: Read the valid flag directly instead of caching it Date: Thu, 12 Dec 2019 11:36:57 +0100 Message-Id: <20191212103658.937528-1-paul.kocialkowski@bootlin.com> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org The RTC has a valid bit in the seconds register that indicates whether power was lost since the pevious time set. This bit is currently read once at probe time, cached and updated with set_time. Howeever, caching the bit may prevent detecting power loss at runtime (which can happen if the RTC's supply is distinct from the the platform's). Writing the seconds register when setting time will clear the bit, so there should be no downside in reading the bit directly instead of caching it. Signed-off-by: Paul Kocialkowski --- drivers/rtc/rtc-hym8563.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/rtc/rtc-hym8563.c b/drivers/rtc/rtc-hym8563.c index 443f6d05ce29..584a7815f246 100644 --- a/drivers/rtc/rtc-hym8563.c +++ b/drivers/rtc/rtc-hym8563.c @@ -78,7 +78,6 @@ struct hym8563 { struct i2c_client *client; struct rtc_device *rtc; - bool valid; #ifdef CONFIG_COMMON_CLK struct clk_hw clkout_hw; #endif @@ -95,15 +94,16 @@ static int hym8563_rtc_read_time(struct device *dev, struct rtc_time *tm) u8 buf[7]; int ret; - if (!hym8563->valid) { - dev_warn(&client->dev, "no valid clock/calendar values available\n"); - return -EPERM; - } - ret = i2c_smbus_read_i2c_block_data(client, HYM8563_SEC, 7, buf); if (ret < 0) return ret; + if (ret & HYM8563_SEC_VL) { + dev_warn(&client->dev, + "no valid clock/calendar values available\n"); + return -EPERM; + } + tm->tm_sec = bcd2bin(buf[0] & HYM8563_SEC_MASK); tm->tm_min = bcd2bin(buf[1] & HYM8563_MIN_MASK); tm->tm_hour = bcd2bin(buf[2] & HYM8563_HOUR_MASK); @@ -157,8 +157,6 @@ static int hym8563_rtc_set_time(struct device *dev, struct rtc_time *tm) if (ret < 0) return ret; - hym8563->valid = true; - return 0; } @@ -556,9 +554,8 @@ static int hym8563_probe(struct i2c_client *client, if (ret < 0) return ret; - hym8563->valid = !(ret & HYM8563_SEC_VL); dev_dbg(&client->dev, "rtc information is %s\n", - hym8563->valid ? "valid" : "invalid"); + (ret & HYM8563_SEC_VL) ? "invalid" : "valid"); hym8563->rtc = devm_rtc_device_register(&client->dev, client->name, &hym8563_rtc_ops, THIS_MODULE); -- 2.24.0