[PARISC] disable cr16 clocksource when multiple CPUs are online
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
index e47e27c..c33b6e0 100644
--- a/arch/parisc/kernel/time.c
+++ b/arch/parisc/kernel/time.c
@@ -99,7 +99,7 @@
* cycles after the IT fires. But it's arbitrary how much time passes
* before we call it "late". I've picked one second.
*/
- if (ticks_elapsed > HZ) {
+ if (unlikely(ticks_elapsed > HZ)) {
/* Scenario 3: very long delay? bad in any case */
printk (KERN_CRIT "timer_interrupt(CPU %d): delayed!"
" cycles %lX rem %lX "
@@ -180,6 +180,8 @@
return get_cycles();
}
+static int cr16_update_callback(void);
+
static struct clocksource clocksource_cr16 = {
.name = "cr16",
.rating = 300,
@@ -187,9 +189,25 @@
.mask = CLOCKSOURCE_MASK(BITS_PER_LONG),
.mult = 0, /* to be set */
.shift = 22,
+ .update_callback = cr16_update_callback,
.is_continuous = 1,
};
+static int cr16_update_callback(void)
+{
+ int change = 0;
+
+ /* since the cr16 cycle counters are not syncronized across CPUs,
+ we'll check if we should switch to a safe clocksource: */
+ if (clocksource_cr16.rating != 0 && num_online_cpus() > 1) {
+ clocksource_cr16.rating = 0;
+ clocksource_reselect();
+ change = 1;
+ }
+
+ return change;
+}
+
/*
* XXX: We can do better than this.
@@ -225,10 +243,6 @@
current_cr16_khz = PAGE0->mem_10msec/10; /* kHz */
clocksource_cr16.mult = clocksource_khz2mult(current_cr16_khz,
clocksource_cr16.shift);
- /* lower the rating if we already know its unstable: */
- if (num_online_cpus()>1)
- clocksource_cr16.rating = 200;
-
clocksource_register(&clocksource_cr16);
if (pdc_tod_read(&tod_data) == 0) {