linux-kernel - [PATCH 21/29] rtc: spear: fix spear_rtc_read

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Message-Id: <20220309162301.61679-21-alexandre.belloni@bootlin.com>
Date:   Wed,  9 Mar 2022 17:22:52 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 21/29] rtc: spear: fix spear_rtc_read_time

The reference manual doesn't specify whether the registers are latched and
they probably aren't, ensure the read time and date are consistent.

Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
---
 drivers/rtc/rtc-spear.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-spear.c b/drivers/rtc/rtc-spear.c
index c395af3ebc91..d4777b01ab22 100644
--- a/drivers/rtc/rtc-spear.c
+++ b/drivers/rtc/rtc-spear.c
@@ -204,8 +204,10 @@ static int spear_rtc_read_time(struct device *dev, struct rtc_time *tm)
 	/* we don't report wday/yday/isdst ... */
 	rtc_wait_not_busy(config);
 
-	time = readl(config->ioaddr + TIME_REG);
-	date = readl(config->ioaddr + DATE_REG);
+	do {
+		time = readl(config->ioaddr + TIME_REG);
+		date = readl(config->ioaddr + DATE_REG);
+	} while (time == readl(config->ioaddr + TIME_REG));
 	tm->tm_sec = (time >> SECOND_SHIFT) & SECOND_MASK;
 	tm->tm_min = (time >> MINUTE_SHIFT) & MIN_MASK;
 	tm->tm_hour = (time >> HOUR_SHIFT) & HOUR_MASK;
-- 
2.35.1