kern/128014: AMD Geode CS5536 watchdog(9) not disabled

Patrick Lamaiziere patpr at davenulle.org
Sat Oct 11 11:40:01 UTC 2008


>Number:         128014
>Category:       kern
>Synopsis:       AMD Geode CS5536 watchdog(9) not disabled
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Oct 11 11:40:00 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Patrick Lamaiziere
>Release:        8.0-CURRENT/i386
>Organization:
>Environment:
FreeBSD malpractice.lamaiziere.net 8.0-CURRENT FreeBSD 8.0-CURRENT #2: Fri Oct 10 11:19:40 CEST 2008     patrick at malpractice.lamaiziere.net:/usr/obj/usr/src/sys/NET5501  i386
>Description:
On the AMD Geode companion chipset CS5536 (by instance on a Soekris Net5501), the hardware watchdog is implemented by a MFGPT timer. When the timer has elapsed, the chipset does a hardware reset.

When the watchdog is disabled, the actual code (sys/i386/i386/geode.c) does not stop the timer, only the the hardware reset is disabled. So if the watchdog is enabled again after the timer has been elapsed, the chipset does a reset and the box reboots immediatly.


>How-To-Repeat:
watchdog -t 16; watchdog -t 0
(wait a bit)
watchdog -t 16 => hardware reset


>Fix:
The attached patch stops and resets the timer when the watchdog is disabled and never disables the hardware reset - if the timer has elapsed it's too late - 

Patch attached with submission follows:

--- geode.c	2008-10-09 20:52:47.000000000 +0200
+++ /usr/src/sys/i386/i386/geode.c	2008-10-10 10:25:47.000000000 +0200
@@ -208,14 +208,11 @@
 static void
 cs5536_watchdog(void *foo __unused, u_int cmd, int *error)
 {
-	u_int u, p;
+	u_int u, p, s;
 	uint16_t a;
 	uint32_t m;
 
 	a = rdmsr(0x5140000d);
-	m = rdmsr(0x51400029);
-	m &= ~(1 << 24);
-	wrmsr(0x51400029, m);
 
 	u = cmd & WD_INTERVAL;
 	if (u >= 30 && u <= 44) {
@@ -228,12 +225,24 @@
 		/* reset counter */
 		outw(a + 4, 0);
 		/* Arm reset mechanism */
+		m = rdmsr(0x51400029);
 		m |= (1 << 24);
 		wrmsr(0x51400029, m);
 		/* Start counter */
 		outw(a + 6, 0x8000);
 
 		*error = 0;
+	} else {
+		/* 
+		 * MFGPT_SETUP is write-once
+		 * Check if the counter has been setup
+		 */
+		s = inw(a + 6);
+		if (s & (1 << 12)) {
+			/* Stop and reset counter */
+			outw(a + 6, 0);
+			outw(a + 4, 0);
+		}
 	}
 }
 


>Release-Note:
>Audit-Trail:
>Unformatted:


More information about the freebsd-bugs mailing list