linux-kernel - [PATCH] rtc: fix ds1388 time corruption

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Date:	Thu, 17 Jun 2010 11:42:50 +0200
From:	Joakim Tjernlund <Joakim.Tjernlund@...nsmode.se>
To:	rtc-linux@...glegroups.com, Paul Gortmaker <p_gortmaker@...oo.com>,
	linux-kernel@...r.kernel.org
Cc:	Joakim Tjernlund <Joakim.Tjernlund@...nsmode.se>
Subject: [PATCH] rtc: fix ds1388 time corruption

The ds1307 driver misreads the ds1388 registers when
checking for 12 or 24 hour mode. Instead of
checking the hour register it reads the minute register.
Therefore the driver thinks minutes >= 40 has the
12HR bit set and resets the minute register by zeroing
the high bits. This results in minutes are reset
to 0-9, jumping back in time 40 or 50 minutes. The
time jump is also written back to the RTC.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@...nsmode.se>
---

This should go to Linus ASAP IMHO.

 drivers/rtc/rtc-ds1307.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index c4ec5c1..a01bbe2 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -775,7 +775,7 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 
 read_rtc:
 	/* read RTC registers */
-	tmp = ds1307->read_block_data(ds1307->client, 0, 8, buf);
+	tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
 	if (tmp != 8) {
 		pr_debug("read error %d\n", tmp);
 		err = -EIO;
@@ -860,7 +860,7 @@ read_rtc:
 		if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 			tmp += 12;
 		i2c_smbus_write_byte_data(client,
-				DS1307_REG_HOUR,
+				ds1307->offset + DS1307_REG_HOUR,
 				bin2bcd(tmp));
 	}
 
-- 
1.7.1

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