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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Alessandro Zummo <a.zummo@towertech.it>,
	Sylvain Chouleur <sylvain.chouleur@intel.com>,
	Patrick McDermott <patrick.mcdermott@libiquity.com>,
	linux-rtc@vger.kernel.org, Eric Wong <e@80x24.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 071/343] rtc: cmos: ignore bogus century byte
Date: Fri, 24 Jan 2020 10:28:09 +0100	[thread overview]
Message-ID: <20200124092929.142447271@linuxfoundation.org> (raw)
In-Reply-To: <20200124092919.490687572@linuxfoundation.org>

From: Eric Wong <e@80x24.org>

[ Upstream commit 2a4daadd4d3e507138f8937926e6a4df49c6bfdc ]

Older versions of Libreboot and Coreboot had an invalid value
(`3' in my case) in the century byte affecting the GM45 in
the Thinkpad X200.  Not everybody's updated their firmwares,
and Linux <= 4.2 was able to read the RTC without problems,
so workaround this by ignoring invalid values.

Fixes: 3c217e51d8a272b9 ("rtc: cmos: century support")

Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Sylvain Chouleur <sylvain.chouleur@intel.com>
Cc: Patrick McDermott <patrick.mcdermott@libiquity.com>
Cc: linux-rtc@vger.kernel.org
Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/rtc/rtc-mc146818-lib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index 2f1772a358ca5..18a6f15e313d8 100644
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -82,7 +82,7 @@ unsigned int mc146818_get_time(struct rtc_time *time)
 	time->tm_year += real_year - 72;
 #endif
 
-	if (century)
+	if (century > 20)
 		time->tm_year += (century - 19) * 100;
 
 	/*
-- 
2.20.1




           reply	other threads:[~2020-01-24  9:48 UTC|newest]

Thread overview: expand[flat|nested]  mbox.gz  Atom feed
 [parent not found: <20200124092919.490687572@linuxfoundation.org>]

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