rtc: ds1307: remove clear of oscillator stop flag (OSF) in probe

[ Upstream commit 4845865 ]

In using CONFIG_RTC_HCTOSYS, rtc_hctosys() will sync the RTC time to the
kernel time as long as rtc_read_time() succeeds. In some power loss
situations, our supercapacitor-backed DS1342 RTC comes up with either an
unpredictable future time or the default 01/01/00 from the datasheet.
The oscillator stop flag (OSF) is set in these scenarios due to the
power loss and can be used to determine the validity of the RTC data.

Some chip types in the ds1307 driver already have OSF handling to
determine whether .read_time provides valid RTC data or returns -EINVAL.

This change removes the clear of the OSF in .probe as the OSF needs to
be preserved to expand the OSF handling to the ds1341 chip type (note
that DS1341 and DS1342 share a datasheet).

Signed-off-by: Meagan Lloyd <meaganlloyd@linux.microsoft.com>
Reviewed-by: Tyler Hicks <code@tyhicks.com>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Link: https://lore.kernel.org/r/1749665656-30108-2-git-send-email-meaganlloyd@linux.microsoft.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Meagan Lloyd

drivers/rtc/rtc-ds1307.c

@@ -1824,10 +1824,8 @@ static int ds1307_probe(struct i2c_client *client)
 		regmap_write(ds1307->regmap, DS1337_REG_CONTROL,
 			     regs[0]);
 
-		/* oscillator fault?  clear flag, and warn */
+		/* oscillator fault? warn */
 		if (regs[1] & DS1337_BIT_OSF) {
-			regmap_write(ds1307->regmap, DS1337_REG_STATUS,
-				     regs[1] & ~DS1337_BIT_OSF);
 			dev_warn(ds1307->dev, "SET TIME!\n");
 		}
 		break;