* [PATCH] rtc: Fix hwclock write fail problem in x86 arch
@ 2021-05-19 9:23 Jingxian He
2021-05-20 8:59 ` Thomas Gleixner
0 siblings, 1 reply; 3+ messages in thread
From: Jingxian He @ 2021-05-19 9:23 UTC (permalink / raw)
To: tglx, mingo, bp, x86, linux-kernel, hpa
Cc: hejie3, hewenliang4, wuxu.wu, hejingxian
When RTC_ALWAYS_BCD is set as 1, the function mc146818_set_time
ignores the reading value of RTC_CONTROL register,
and assumes that RTC always operates in binary mode.
However, the mc146818 development manual says that:
if !(CMOS_READ(RTC_CONTROL) & 0x04), then
the rtc time is in binary mode;
if (CMOS_READ(RTC_CONTROL) & 0x04), then
the rtc time is in bcd mode.
We use 'hwclock -w' to set the RTC from the system time
at our x86 machines, and we find that when
(CMOS_READ(RTC_CONTROL) & 0x04) is equal to 1,
'hwclock -w' will fail to set the RTC.
We change the RTC_ALWAYS_BCD to 0 to parse the rtc
time according to the read value of RTC_CONTROL register.
Signed-off-by: Jingxian He <hejingxian@huawei.com>
Signed-off-by: Jie He <hejie3@huawei.com>
---
arch/x86/include/asm/mc146818rtc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/mc146818rtc.h b/arch/x86/include/asm/mc146818rtc.h
index 9719800..63cf0d5 100644
--- a/arch/x86/include/asm/mc146818rtc.h
+++ b/arch/x86/include/asm/mc146818rtc.h
@@ -10,7 +10,7 @@
#ifndef RTC_PORT
#define RTC_PORT(x) (0x70 + (x))
-#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */
+#define RTC_ALWAYS_BCD 0
#endif
#if defined(CONFIG_X86_32)
--
2.9.5
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] rtc: Fix hwclock write fail problem in x86 arch
2021-05-19 9:23 [PATCH] rtc: Fix hwclock write fail problem in x86 arch Jingxian He
@ 2021-05-20 8:59 ` Thomas Gleixner
0 siblings, 0 replies; 3+ messages in thread
From: Thomas Gleixner @ 2021-05-20 8:59 UTC (permalink / raw)
To: Jingxian He
Cc: mingo, bp, x86, linux-kernel, hpa, hejie3, hewenliang4, wuxu.wu,
hejingxian, Sang Yan
On Wed, May 19 2021 at 17:23, Jingxian He wrote:
So at 17:19 this very same patch was posted by Sang Yan <sangyan@huawei.com>
https://lore.kernel.org/r/20210519091908.513593-1-sangyan@huawei.com
Can you please coordinate patch posting internaly?
It has the same broken SOB chain as this one:
> Signed-off-by: Jingxian He <hejingxian@huawei.com>
> Signed-off-by: Jie He <hejie3@huawei.com>
See Documentation/process/submitting-patches.rst
Thanks,
tglx
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] rtc: Fix hwclock write fail problem in x86 arch
@ 2021-05-19 9:19 Sang Yan
0 siblings, 0 replies; 3+ messages in thread
From: Sang Yan @ 2021-05-19 9:19 UTC (permalink / raw)
To: tglx, mingo, bp, x86, linux-kernel, hpa
Cc: hejie3, hewenliang4, wuxu.wu, hejingxian
From: Jingxian He <hejingxian@huawei.com>
When RTC_ALWAYS_BCD is set as 1, the function mc146818_set_time
ignores the reading value of RTC_CONTROL register,
and assumes that RTC always operates in binary mode.
However, the mc146818 development manual says that:
if !(CMOS_READ(RTC_CONTROL) & 0x04), then
the rtc time is in binary mode;
if (CMOS_READ(RTC_CONTROL) & 0x04), then
the rtc time is in bcd mode.
We use 'hwclock -w' to set the RTC from the system time
at our x86 machines, and we find that when
(CMOS_READ(RTC_CONTROL) & 0x04) is equal to 1,
'hwclock -w' will fail to set the RTC.
We change the RTC_ALWAYS_BCD to 0 to parse the rtc
time according to the read value of RTC_CONTROL register.
Signed-off-by: Jingxian He <hejingxian@huawei.com>
Signed-off-by: Jie He <hejie3@huawei.com>
---
arch/x86/include/asm/mc146818rtc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/mc146818rtc.h b/arch/x86/include/asm/mc146818rtc.h
index 9719800..63cf0d5 100644
--- a/arch/x86/include/asm/mc146818rtc.h
+++ b/arch/x86/include/asm/mc146818rtc.h
@@ -10,7 +10,7 @@
#ifndef RTC_PORT
#define RTC_PORT(x) (0x70 + (x))
-#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */
+#define RTC_ALWAYS_BCD 0
#endif
#if defined(CONFIG_X86_32)
--
2.9.5
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2021-05-20 8:59 ` Thomas Gleixner
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