cpuidle, OMAP3: Push RCU-idle into driver

Doing RCU-idle outside the driver, only to then teporarily enable it
again before going idle is suboptimal.

Notably the cpu_pm_*() calls implicitly re-enable RCU for a bit.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20230112195539.883561913@infradead.org

arch/arm/mach-omap2/cpuidle34xx.c

@@ -133,7 +133,9 @@ static int omap3_enter_idle(struct cpuidle_device *dev,
 	}
 
 	/* Execute ARM wfi */
+	ct_idle_enter();
 	omap_sram_idle();
+	ct_idle_exit();
 
 	/*
 	 * Call idle CPU PM enter notifier chain to restore
@@ -265,6 +267,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 	.owner            = THIS_MODULE,
 	.states = {
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 2 + 2,
 			.target_residency = 5,
@@ -272,6 +275,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 			.desc		  = "MPU ON + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 10 + 10,
 			.target_residency = 30,
@@ -279,6 +283,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 			.desc		  = "MPU ON + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 50 + 50,
 			.target_residency = 300,
@@ -286,6 +291,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 			.desc		  = "MPU RET + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 1500 + 1800,
 			.target_residency = 4000,
@@ -293,6 +299,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 			.desc		  = "MPU OFF + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 2500 + 7500,
 			.target_residency = 12000,
@@ -300,6 +307,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 			.desc		  = "MPU RET + CORE RET",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 3000 + 8500,
 			.target_residency = 15000,
@@ -307,6 +315,7 @@ static struct cpuidle_driver omap3_idle_driver = {
 			.desc		  = "MPU OFF + CORE RET",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 10000 + 30000,
 			.target_residency = 30000,
@@ -328,6 +337,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 	.owner            = THIS_MODULE,
 	.states = {
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 110 + 162,
 			.target_residency = 5,
@@ -335,6 +345,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 			.desc		  = "MPU ON + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 106 + 180,
 			.target_residency = 309,
@@ -342,6 +353,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 			.desc		  = "MPU ON + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 107 + 410,
 			.target_residency = 46057,
@@ -349,6 +361,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 			.desc		  = "MPU RET + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 121 + 3374,
 			.target_residency = 46057,
@@ -356,6 +369,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 			.desc		  = "MPU OFF + CORE ON",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 855 + 1146,
 			.target_residency = 46057,
@@ -363,6 +377,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 			.desc		  = "MPU RET + CORE RET",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 7580 + 4134,
 			.target_residency = 484329,
@@ -370,6 +385,7 @@ static struct cpuidle_driver omap3430_idle_driver = {
 			.desc		  = "MPU OFF + CORE RET",
 		},
 		{
+			.flags		  = CPUIDLE_FLAG_RCU_IDLE,
 			.enter		  = omap3_enter_idle_bm,
 			.exit_latency	  = 7505 + 15274,
 			.target_residency = 484329,