From 206778f7a8412b3f694cee3d3931e4d77cd5af7b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Guido=20G=C3=BCnther?= <agx@sigxcpu.org>
Date: Fri, 20 Dec 2019 12:50:16 +0100
Subject: [PATCH] rtc: m41t80: Clear oscillator fault bit during probe
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This make sure we don't read a bad value later on.

Signed-off-by: Guido Günther <guido.gunther@puri.sm>
---
 drivers/rtc/rtc-m41t80.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index 160dcf68e64ebd..71a52c75793565 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -959,6 +959,17 @@ static int m41t80_probe(struct i2c_client *client,
 		return rc;
 	}
 
+	/* Make sure OF (osciallator failure) is  cleared */
+	rc = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
+
+	if (rc >= 0)
+		rc = i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS,
+					       rc & ~M41T80_FLAGS_OF);
+	if (rc < 0) {
+		dev_err(&client->dev, "Can't clear OF bit\n");
+		return rc;
+	}
+
 #ifdef CONFIG_RTC_DRV_M41T80_WDT
 	if (m41t80_data->features & M41T80_FEATURE_HT) {
 		save_client = client;