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Re: [PATCH] RTC: Fix CMOS time error after writing /proc/acpi/alarm

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[view original message]
From: Chen, Huacai <huacai.chen@...>
To: <linux-acpi@...>, <linux-pm@...>, <rtc-linux@...>, <lenb@...>, <p_gortmaker@...>, <a.zummo@...>
Cc: <linux-kernel@...>
Subject: [PATCH] RTC: Fix CMOS time error after writing /proc/acpi/alarm
Date: Monday, June 23, 2008 - 6:52 am

From: Huacai Chen <huacai.chen@intel.com>


When writing /proc/acpi/alarm in adjust mode, e.g.

	echo "+0000-00-00 00:00:15" >/proc/acpi/alarm

The "century" field should be read and added to "year" field before

writing, otherwise the CMOS time will go back to 2000 years ago, e.g.

	# cat /proc/acpi/alarm

	0008-06-21 11:38:46

Then the system time may be reset to the date of manufacture after

rebooting. This patch fixed this issue.


Signed-off-by: Huacai Chen <huacai.chen@intel.com>

Acked-by: Pavel Machek <pavel@suse.cz>

---

diff --git a/drivers/acpi/sleep/proc.c b/drivers/acpi/sleep/proc.c

index 224c57c..c9fdf7b 100644

--- a/drivers/acpi/sleep/proc.c

+++ b/drivers/acpi/sleep/proc.c

@@ -315,8 +315,11 @@ acpi_system_write_alarm(struct file *file,

 		cmos_bcd_write(day, acpi_gbl_FADT.day_alarm,

rtc_control);

 	if (acpi_gbl_FADT.month_alarm)

 		cmos_bcd_write(mo, acpi_gbl_FADT.month_alarm,

rtc_control);

-	if (acpi_gbl_FADT.century)

+	if (acpi_gbl_FADT.century) {

+		if (adjust)

+			yr += cmos_bcd_read(acpi_gbl_FADT.century,

rtc_control) * 100;

 		cmos_bcd_write(yr / 100, acpi_gbl_FADT.century,

rtc_control);

+	}

 	/* enable the rtc alarm interrupt */

 	rtc_control |= RTC_AIE;

 	CMOS_WRITE(rtc_control, RTC_CONTROL);

---

This is for Linux 2.6.26-rc7.

--
[view original message]
From: Alessandro Zummo <alessandro.zummo@...>
To: <rtc-linux@...>
Cc: <huacai.chen@...>, <linux-acpi@...>, <linux-pm@...>, <lenb@...>, <p_gortmaker@...>, <linux-kernel@...>, <akpm@...>
Subject: Re: [PATCH] RTC: Fix CMOS time error after writing /proc/acpi/alarm
Date: Wednesday, June 25, 2008 - 4:44 am

On Mon, 23 Jun 2008 18:52:21 +0800


 Acked-by: Alessandro Zummo <a.zummo@towertech.it>


-- 


 Best regards,


 Alessandro Zummo,

  Tower Technologies - Torino, Italy


  http://www.towertech.it


--
[view original message]
From: Zhao Yakui <yakui.zhao@...>
To: Chen, Huacai <huacai.chen@...>
Cc: <linux-acpi@...>, <linux-pm@...>, <rtc-linux@...>, <lenb@...>, <p_gortmaker@...>, <a.zummo@...>, <linux-kernel@...>
Subject: Re: [PATCH] RTC: Fix CMOS time error after writing /proc/acpi/alarm
Date: Tuesday, June 24, 2008 - 2:37 am

--
Previous thread: [BUG] While changing the cpufreq governor, kernel hits a bug in workqueue.c by Nageswara R Sastry on Monday, June 23, 2008 - 6:51 am. (22 messages)

Next thread: [PATCH] cpia2: use request_firmware() by David Woodhouse on Monday, June 23, 2008 - 7:03 am. (2 messages)