* [PATCH 4.19 143/639] rtc: cmos: ignore bogus century byte
[not found] <20200124093047.008739095@linuxfoundation.org>
@ 2020-01-24 9:25 ` Greg Kroah-Hartman
2020-01-25 12:04 ` Pavel Machek
0 siblings, 1 reply; 2+ messages in thread
From: Greg Kroah-Hartman @ 2020-01-24 9:25 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Alexandre Belloni, Alessandro Zummo,
Sylvain Chouleur, Patrick McDermott, linux-rtc, Eric Wong,
Sasha Levin
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 4.19 143/639] rtc: cmos: ignore bogus century byte
2020-01-24 9:25 ` [PATCH 4.19 143/639] rtc: cmos: ignore bogus century byte Greg Kroah-Hartman
@ 2020-01-25 12:04 ` Pavel Machek
0 siblings, 0 replies; 2+ messages in thread
From: Pavel Machek @ 2020-01-25 12:04 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, stable, Alexandre Belloni, Alessandro Zummo,
Sylvain Chouleur, Patrick McDermott, linux-rtc, Eric Wong,
Sasha Levin
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Hi!
> 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.
Should it print a warning so that wrong BIOSes are eventually fixed?
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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2020-01-24 9:25 ` [PATCH 4.19 143/639] rtc: cmos: ignore bogus century byte Greg Kroah-Hartman
2020-01-25 12:04 ` Pavel Machek
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