--- a/arch/mips/kernel/cevt-r4k.c +++ b/arch/mips/kernel/cevt-r4k.c @@ -13,6 +13,22 @@ #include #include +/* + * 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;