[coreboot] New patch to review: 1b30ff6 i82801gx: read RTC status register to prevent IRQ storm

Sven Schnelle (svens@stackframe.org) gerrit at coreboot.org
Wed Jun 29 15:11:01 CEST 2011

Sven Schnelle (svens at stackframe.org) just uploaded a new patch set to gerrit, which you can find at


commit 1b30ff69f083f2416abfa0f0977ea315368d28e6
Author: Sven Schnelle <svens at stackframe.org>
Date:   Wed Jun 29 15:05:28 2011 +0200

    i82801gx: read RTC status register to prevent IRQ storm
    My Thinkpad appeared dead. After investigation, it turned out
    that the RTC Alarm was triggering an RTC PM1 SMI, but the SMI
    handler didn't read the status register, so it was triggered again.
    This is a really nasty situation, as it means you have to dissemble
    your Notebook just to unplug the RTC battery.
    Change-Id: I5ac611e8a72deb5f38c86486dbe0693804935723
    Signed-off-by: Sven Schnelle <svens at stackframe.org>
 src/southbridge/intel/i82801gx/smihandler.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/src/southbridge/intel/i82801gx/smihandler.c b/src/southbridge/intel/i82801gx/smihandler.c
index 434bfeb..81a88d8 100644
--- a/src/southbridge/intel/i82801gx/smihandler.c
+++ b/src/southbridge/intel/i82801gx/smihandler.c
@@ -26,6 +26,7 @@
 #include <cpu/x86/cache.h>
 #include <cpu/x86/smm.h>
 #include <device/pci_def.h>
+#include <pc80/mc146818rtc.h>
 #include "i82801gx.h"
 /* I945 */
@@ -423,6 +424,11 @@ static void southbridge_smi_pm1(unsigned int node, smm_state_save_area_t *state_
 		reg32 = (7 << 10) | (1 << 13);
 		outl(reg32, pmbase + PM1_CNT);
+	if (pm1_sts & RTC_STS) {
+		/* read RTC status register to disable the interrupt */
+		printk(BIOS_DEBUG, "RTC IRQ status: %02X\n", cmos_read(RTC_REG_C));
+	}
 static void southbridge_smi_gpe0(unsigned int node, smm_state_save_area_t *state_save)

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