* [PATCH] rtc: cmos: ignore bogus century byte
@ 2019-01-06 8:21 Eric Wong
2019-01-10 21:33 ` Alexandre Belloni
2019-01-22 18:06 ` Alexandre Belloni
0 siblings, 2 replies; 4+ messages in thread
From: Eric Wong @ 2019-01-06 8:21 UTC (permalink / raw)
To: Alexandre Belloni, Alessandro Zummo
Cc: Sylvain Chouleur, Patrick McDermott, linux-rtc, linux-kernel
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>
---
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 2f1772a358ca..18a6f15e313d 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;
/*
--
EW
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: cmos: ignore bogus century byte
2019-01-06 8:21 [PATCH] rtc: cmos: ignore bogus century byte Eric Wong
@ 2019-01-10 21:33 ` Alexandre Belloni
2019-01-10 21:56 ` Eric Wong
2019-01-22 18:06 ` Alexandre Belloni
1 sibling, 1 reply; 4+ messages in thread
From: Alexandre Belloni @ 2019-01-10 21:33 UTC (permalink / raw)
To: Eric Wong
Cc: Alessandro Zummo, Sylvain Chouleur, Patrick McDermott, linux-rtc,
linux-kernel
On 06/01/2019 08:21:03+0000, Eric Wong wrote:
> 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.
>
Does this mean that it is set to an invalid value and that in is not
getting updated properly in mc146818_set_time?
> 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>
> ---
> 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 2f1772a358ca..18a6f15e313d 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;
>
> /*
> --
> EW
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: cmos: ignore bogus century byte
2019-01-10 21:33 ` Alexandre Belloni
@ 2019-01-10 21:56 ` Eric Wong
0 siblings, 0 replies; 4+ messages in thread
From: Eric Wong @ 2019-01-10 21:56 UTC (permalink / raw)
To: Alexandre Belloni, Patrick McDermott
Cc: Alessandro Zummo, Sylvain Chouleur, linux-rtc, linux-kernel
Alexandre Belloni <alexandre.belloni@bootlin.com> wrote:
> Does this mean that it is set to an invalid value and that in is not
> getting updated properly in mc146818_set_time?
It seems to be set/updated without trouble while the machine is
on. It's only on a cold boot (from poweroff or hibernate) that
the value is invalid.
Patrick may be able to fill you in on more details.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] rtc: cmos: ignore bogus century byte
2019-01-06 8:21 [PATCH] rtc: cmos: ignore bogus century byte Eric Wong
2019-01-10 21:33 ` Alexandre Belloni
@ 2019-01-22 18:06 ` Alexandre Belloni
1 sibling, 0 replies; 4+ messages in thread
From: Alexandre Belloni @ 2019-01-22 18:06 UTC (permalink / raw)
To: Eric Wong
Cc: Alessandro Zummo, Sylvain Chouleur, Patrick McDermott, linux-rtc,
linux-kernel
On 06/01/2019 08:21:03+0000, Eric Wong wrote:
> 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>
> ---
> drivers/rtc/rtc-mc146818-lib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
Applied, thanks.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-01-06 8:21 [PATCH] rtc: cmos: ignore bogus century byte Eric Wong
2019-01-10 21:33 ` Alexandre Belloni
2019-01-10 21:56 ` Eric Wong
2019-01-22 18:06 ` Alexandre Belloni
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