openwrt/target/linux/mvebu/patches-5.10/800-cpuidle-mvebu-indicate-failure-to-enter-deeper-sleep.patch

From c28b2d367da8a471482e6a4aa8337ab6369a80c2 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Sat, 3 Oct 2015 09:13:05 +0100
Subject: cpuidle: mvebu: indicate failure to enter deeper sleep states

The cpuidle ->enter method expects the return value to be the sleep
state we entered.  Returning negative numbers or other codes is not
permissible since coupled CPU idle was merged.

At least some of the mvebu_v7_cpu_suspend() implementations return the
value from cpu_suspend(), which returns zero if the CPU vectors back
into the kernel via cpu_resume() (the success case), or the non-zero
return value of the suspend actor, or one (failure cases).

We do not want to be returning the failure case value back to CPU idle
as that indicates that we successfully entered one of the deeper idle
states.  Always return zero instead, indicating that we slept for the
shortest amount of time.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/cpuidle/cpuidle-mvebu-v7.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/cpuidle/cpuidle-mvebu-v7.c
+++ b/drivers/cpuidle/cpuidle-mvebu-v7.c
@@ -39,8 +39,12 @@ static int mvebu_v7_enter_idle(struct cp
 	ret = mvebu_v7_cpu_suspend(deepidle);
 	cpu_pm_exit();
 
+	/*
+	 * If we failed to enter the desired state, indicate that we
+	 * slept lightly.
+	 */
 	if (ret)
-		return ret;
+		return 0;
 
 	return index;
 }