UPSTREAM: cpuidle: teo: Simplify handling of total events count

Instead of computing the total events count from scratch every time,
decay it and add a PULSE value to it in teo_update().

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/9388883.CDJkKcVGEf@rjwysocki.net
(cherry picked from commit ddcfa79)

Bug: 450671466
Change-Id: I06467a8c0e85cfe432c61b5d7a68a080cf250bc6
Signed-off-by: Reka Norman <rekanorman@google.com>

Author: rafaeljw

drivers/cpuidle/governors/teo.c

@@ -189,8 +189,6 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 		}
 	}
 
-	cpu_data->total = 0;
-
 	/*
 	 * Decay the "hits" and "intercepts" metrics for all of the bins and
 	 * find the bins that the sleep length and the measured idle duration
@@ -202,8 +200,6 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 		bin->hits -= bin->hits >> DECAY_SHIFT;
 		bin->intercepts -= bin->intercepts >> DECAY_SHIFT;
 
-		cpu_data->total += bin->hits + bin->intercepts;
-
 		target_residency_ns = drv->states[i].target_residency_ns;
 
 		if (target_residency_ns <= cpu_data->sleep_length_ns) {
@@ -228,6 +224,7 @@ static void teo_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 			cpu_data->tick_intercepts += PULSE;
 	}
 
+	cpu_data->total -= cpu_data->total >> DECAY_SHIFT;
 	cpu_data->total += PULSE;
 }