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Index: linux-2.6.30.5/arch/mips/kernel/cevt-r4k.c
===================================================================
--- linux-2.6.30.5.orig/arch/mips/kernel/cevt-r4k.c 2009-08-16 23:19:38.000000000 +0200
+++ linux-2.6.30.5/arch/mips/kernel/cevt-r4k.c 2009-09-02 18:26:26.000000000 +0200
@@ -21,6 +21,22 @@
#ifndef CONFIG_MIPS_MT_SMTC
+/*
+ * Compare interrupt can be routed and latched outside the core,
+ * so a single execution hazard barrier may not be enough to give
+ * it time to clear as seen in the Cause register. 4 time the
+ * pipeline depth seems reasonably conservative, and empirically
+ * works better in configurations with high CPU/bus clock ratios.
+ */
+
+#define compare_change_hazard() \
+ do { \
+ irq_disable_hazard(); \
+ irq_disable_hazard(); \
+ irq_disable_hazard(); \
+ irq_disable_hazard(); \
+ } while (0)
+
static int mips_next_event(unsigned long delta,
struct clock_event_device *evt)
{
@@ -30,6 +46,7 @@
cnt = read_c0_count();
cnt += delta;
write_c0_compare(cnt);
+ compare_change_hazard();
res = ((int)(read_c0_count() - cnt) > 0) ? -ETIME : 0;
return res;
}
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