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From: =?UTF-8?q?Cs=C3=B3k=C3=A1s=2C=20Bence?= <csokas.bence@prolan.hu>
To: <linux-rtc@vger.kernel.org>, <linux-kernel@vger.kernel.org>
CC: =?UTF-8?q?Cs=C3=B3k=C3=A1s=2C=20Bence?= <csokas.bence@prolan.hu>,
	=?UTF-8?q?Szentendrei=2C=20Tam=C3=A1s?= <szentendrei.tamas@prolan.hu>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>
Subject: [PATCH v2 2/2] rtc: ds1307: Clamp year to valid BCD (0-99) in `set_time()`
Date: Tue, 11 Jun 2024 09:24:09 +0200
Message-ID: <20240611072411.671600-2-csokas.bence@prolan.hu>
In-Reply-To: <20240611072411.671600-1-csokas.bence@prolan.hu>
References: <20240611072411.671600-1-csokas.bence@prolan.hu>
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`tm_year` may go up to 299 if the device supports the
century bit. Therefore, subtracting may not give us
a valid 2-digit number, but modulo does.

Co-developed-by: Szentendrei, Tamás <szentendrei.tamas@prolan.hu>
Signed-off-by: Szentendrei, Tamás <szentendrei.tamas@prolan.hu>
Signed-off-by: Csókás, Bence <csokas.bence@prolan.hu>
---
 drivers/rtc/rtc-ds1307.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index bdb7b201a160..872e0b679be4 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -359,7 +359,7 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 	regs[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 
 	/* assume 20YY not 19YY */
-	tmp = t->tm_year - 100;
+	tmp = t->tm_year % 100;
 	regs[DS1307_REG_YEAR] = bin2bcd(tmp);
 
 	if (chip->century_enable_bit)
-- 
2.34.1