[tip: sched/core] cpuidle, dt: Push RCU-idle into driver

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     0c5ffc3d7b15978c6b184938cd6b8af06e436424
Gitweb:        https://git.kernel.org/tip/0c5ffc3d7b15978c6b184938cd6b8af06e436424
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Thu, 12 Jan 2023 20:43:26 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 13 Jan 2023 11:48:00 +01:00

cpuidle, dt: Push RCU-idle into driver

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

Notably: this converts all dt_init_idle_driver() and
__CPU_PM_CPU_IDLE_ENTER() users for they are inextrably intertwined.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: Tony Lindgren <tony@xxxxxxxxxxx>
Tested-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Acked-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230112195540.068981667@xxxxxxxxxxxxx
---
 drivers/acpi/processor_idle.c        | 2 ++
 drivers/cpuidle/cpuidle-big_little.c | 8 ++++++--
 drivers/cpuidle/dt_idle_states.c     | 2 +-
 include/linux/cpuidle.h              | 2 ++
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 7bf882f..566f7db 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1219,6 +1219,8 @@ static int acpi_processor_setup_lpi_states(struct acpi_processor *pr)
 		state->target_residency = lpi->min_residency;
 		if (lpi->arch_flags)
 			state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+		if (i != 0 && lpi->entry_method == ACPI_CSTATE_FFH)
+			state->flags |= CPUIDLE_FLAG_RCU_IDLE;
 		state->enter = acpi_idle_lpi_enter;
 		drv->safe_state_index = i;
 	}
diff --git a/drivers/cpuidle/cpuidle-big_little.c b/drivers/cpuidle/cpuidle-big_little.c
index abe5118..fffd4ed 100644
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -64,7 +64,8 @@ static struct cpuidle_driver bl_idle_little_driver = {
 		.enter			= bl_enter_powerdown,
 		.exit_latency		= 700,
 		.target_residency	= 2500,
-		.flags			= CPUIDLE_FLAG_TIMER_STOP,
+		.flags			= CPUIDLE_FLAG_TIMER_STOP |
+					  CPUIDLE_FLAG_RCU_IDLE,
 		.name			= "C1",
 		.desc			= "ARM little-cluster power down",
 	},
@@ -85,7 +86,8 @@ static struct cpuidle_driver bl_idle_big_driver = {
 		.enter			= bl_enter_powerdown,
 		.exit_latency		= 500,
 		.target_residency	= 2000,
-		.flags			= CPUIDLE_FLAG_TIMER_STOP,
+		.flags			= CPUIDLE_FLAG_TIMER_STOP |
+					  CPUIDLE_FLAG_RCU_IDLE,
 		.name			= "C1",
 		.desc			= "ARM big-cluster power down",
 	},
@@ -124,11 +126,13 @@ static int bl_enter_powerdown(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int idx)
 {
 	cpu_pm_enter();
+	ct_idle_enter();
 
 	cpu_suspend(0, bl_powerdown_finisher);
 
 	/* signals the MCPM core that CPU is out of low power state */
 	mcpm_cpu_powered_up();
+	ct_idle_exit();
 
 	cpu_pm_exit();
 
diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c
index 7ca3d7d..02aa0b3 100644
--- a/drivers/cpuidle/dt_idle_states.c
+++ b/drivers/cpuidle/dt_idle_states.c
@@ -77,7 +77,7 @@ static int init_state_node(struct cpuidle_state *idle_state,
 	if (err)
 		desc = state_node->name;
 
-	idle_state->flags = 0;
+	idle_state->flags = CPUIDLE_FLAG_RCU_IDLE;
 	if (of_property_read_bool(state_node, "local-timer-stop"))
 		idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
 	/*
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index fce4762..0ddc11e 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -289,7 +289,9 @@ extern s64 cpuidle_governor_latency_req(unsigned int cpu);
 	if (!is_retention)						\
 		__ret =  cpu_pm_enter();				\
 	if (!__ret) {							\
+		ct_idle_enter();					\
 		__ret = low_level_idle_enter(state);			\
+		ct_idle_exit();						\
 		if (!is_retention)					\
 			cpu_pm_exit();					\
 	}								\