1 files changed, 65 insertions, 0 deletions
diff --git a/target/linux/ar71xx/patches-2.6.27/902-mips_clocksource_init_war.patch b/target/linux/ar71xx/patches-2.6.27/902-mips_clocksource_init_war.patch
new file mode 100644
index 000000000..bdf0d0fb6
--- /dev/null
+++ b/target/linux/ar71xx/patches-2.6.27/902-mips_clocksource_init_war.patch
@@ -0,0 +1,65 @@
+--- a/arch/mips/kernel/cevt-r4k.c
++++ b/arch/mips/kernel/cevt-r4k.c
+@@ -13,6 +13,22 @@
+ #include <asm/smtc_ipi.h>
+ #include <asm/time.h>
+ 
++/*
++ * 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)
+ {
+@@ -28,6 +44,7 @@
+ 	cnt = read_c0_count();
+ 	cnt += delta;
+ 	write_c0_compare(cnt);
++	compare_change_hazard();
+ 	res = ((int)(read_c0_count() - cnt) > 0) ? -ETIME : 0;
+ #ifdef CONFIG_MIPS_MT_SMTC
+ 	evpe(vpflags);
+@@ -187,7 +204,7 @@
+ 	 */
+ 	if (c0_compare_int_pending()) {
+ 		write_c0_compare(read_c0_count());
+-		irq_disable_hazard();
++		compare_change_hazard();
+ 		if (c0_compare_int_pending())
+ 			return 0;
+ 	}
+@@ -196,7 +213,7 @@
+ 		cnt = read_c0_count();
+ 		cnt += delta;
+ 		write_c0_compare(cnt);
+-		irq_disable_hazard();
++		compare_change_hazard();
+ 		if ((int)(read_c0_count() - cnt) < 0)
+ 		    break;
+ 		/* increase delta if the timer was already expired */
+@@ -205,11 +222,12 @@
+ 	while ((int)(read_c0_count() - cnt) <= 0)
+ 		;	/* Wait for expiry  */
+ 
++	compare_change_hazard();
+ 	if (!c0_compare_int_pending())
+ 		return 0;
+ 
+ 	write_c0_compare(read_c0_count());
+-	irq_disable_hazard();
++	compare_change_hazard();
+ 	if (c0_compare_int_pending())
+ 		return 0;
+