I applied the attached patch (from Ubuntu) to the latest 2.6.22 kernel from
Sid and it resolved the problem. Could this be looked into?
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diff -urp a/init/calibrate.c b/init/calibrate.c
--- a/init/calibrate.c 2006-10-02 11:39:32.000000000 -0400
+++ b/init/calibrate.c 2007-01-27 16:39:35.000000000 -0500
@@ -1,5 +1,7 @@
/* calibrate.c: default delay calibration
*
+ * vim:sw=8 noet
+ *
* Excised from init/main.c
* Copyright (C) 1991, 1992 Linus Torvalds
*/
@@ -7,9 +9,36 @@
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/init.h>
+#include <linux/dmi.h>
+#include <asm/io.h>
#include <asm/timex.h>
+/* On Macbook we have trouble calibrating the delay loop due to excessive
+ * latency in the system management interrupt. We fix this problem by
+ * disabling the "legacy USB" function of the SMC during delay loop
+ * calibration. From Intel ICH7 manual, this is bit 3 of SMI_EN register
+ * located at 0x430.
+ */
+static int __initdata macbook_calibrate_quirk;
+
+static int __init init_macbook_calibrate_quirk (struct dmi_system_id *d)
+{
+ printk(KERN_WARNING "%s detected (calibration quirk enabled)\n",
+ d->ident);
+ macbook_calibrate_quirk = 1;
+ return 0;
+}
+
+static struct dmi_system_id __initdata calibrate_quirks[] = {
+ {
+ .callback = init_macbook_calibrate_quirk,
+ .ident = "Apple MacBook",
+ .matches = {DMI_MATCH(DMI_PRODUCT_NAME, "MacBook1,1"),},
+ },
+ {},
+};
+
static unsigned long preset_lpj;
static int __init lpj_setup(char *str)
{
@@ -37,8 +66,16 @@ static unsigned long __devinit calibrate
unsigned long tsc_rate_min, tsc_rate_max;
unsigned long good_tsc_sum = 0;
unsigned long good_tsc_count = 0;
+ unsigned long saved_smi_en = 0;
int i;
+ if (macbook_calibrate_quirk)
+ {
+ saved_smi_en = inl(0x430);
+ /* mask out bit 3 */
+ outl(saved_smi_en & ~8, 0x430);
+ }
+
if (read_current_timer(&pre_start) < 0 )
return 0;
@@ -94,6 +131,9 @@ static unsigned long __devinit calibrate
}
}
+ if (macbook_calibrate_quirk)
+ outl(saved_smi_en, 0x430);
+
if (good_tsc_count)
return (good_tsc_sum/good_tsc_count);
@@ -117,6 +157,8 @@ void __devinit calibrate_delay(void)
unsigned long ticks, loopbit;
int lps_precision = LPS_PREC;
+ dmi_check_system(calibrate_quirks);
+
if (preset_lpj) {
loops_per_jiffy = preset_lpj;
printk("Calibrating delay loop (skipped)... "
