Implement waiting using WFET

diff --git a/drivers/cpuidle/poll_state.c b/drivers/cpuidle/poll_state.c
index 61df2395585ed685fb324e1935df7f4830b05362..24acd9d093f18431ec3f87019a9e6ea81419f5a9 100644 (file)
--- a/drivers/cpuidle/poll_state.c
+++ b/drivers/cpuidle/poll_state.c
@@ -8,44 +8,41 @@
 #include <linux/sched/clock.h>
 #include <linux/sched/idle.h>
 
-#ifdef CONFIG_ARM64
-/*
- * POLL_IDLE_RELAX_COUNT determines how often we check for timeout
- * while polling for TIF_NEED_RESCHED in thread_info->flags.
- *
- * Set this to a low value since arm64, instead of polling, uses a
- * event based mechanism.
- */
-#define POLL_IDLE_RELAX_COUNT  1
-#else
-#define POLL_IDLE_RELAX_COUNT  200
-#endif
-
 static int __cpuidle poll_idle(struct cpuidle_device *dev,
                               struct cpuidle_driver *drv, int index)
 {
        u64 time_start;
 
-       time_start = local_clock_noinstr();
+       time_start = get_cycles();
 
        dev->poll_time_limit = false;
 
        raw_local_irq_enable();
        if (!current_set_polling_and_test()) {
-               u64 limit;
+               u64 end;
 
-               limit = cpuidle_poll_time(drv, dev);
+               end = start + NSECS_TO_CYCLES(cpuidle_poll_time(drv, dev));
 
                while (!need_resched()) {
-                       unsigned int loop_count = 0;
-                       if (local_clock_noinstr() - time_start > limit) {
-                               dev->poll_time_limit = true;
-                               break;
+
+                       if (alternative_has_cap_unlikely(ARM64_HAS_WFXT)) {
+
+                               /* We can power down for a configurable interval while waiting for event */
+                               while (!need_resched() && get_cycles() < end)
+                                               wfet(end);
+
+                       } else if (arch_timer_evtstrm_available()) {
+
+                               /* We can power down for a ARCH_TIMER_EVT_STREAM_PERIOD_US time interval while waiting */
+                               while (!need_resched() && (get_cycles() < end)
+                                               wfe();
+                       } else {
+
+                               /* No hardware wait mechanism. Do a polling loop */
+                               while (!need_resched() && get_cycles() < end)
+                                       cpu_relax;
                        }
 
-                       smp_cond_load_relaxed(&current_thread_info()->flags,
-                                             VAL & _TIF_NEED_RESCHED ||
-                                             loop_count++ >= POLL_IDLE_RELAX_COUNT);
                }
        }
        raw_local_irq_disable();