ARM: 8586/1: cpuidle: make arm_cpuidle_suspend() a bit more efficient

Currently, we check cpuidle_ops.suspend every time when entering a
low-power idle state. But this check could be avoided in this hot path
by moving it into arm_cpuidle_read_ops() to reduce arm_cpuidle_suspend
overhead a bit.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c
index 2129b297ec20ed6a7e798b941dab2e9e3ccb740b..7dccc964d75f2fff2bdbfa89c4b3d0cc7bb92e61 100644 (file)
--- a/arch/arm/kernel/cpuidle.c
+++ b/arch/arm/kernel/cpuidle.c
@@ -47,18 +47,13 @@ int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
  * This function calls the underlying arch specific low level PM code as
  * registered at the init time.
  *
- * Returns -EOPNOTSUPP if no suspend callback is defined, the result of the
- * callback otherwise.
+ * Returns the result of the suspend callback.
  */
 int arm_cpuidle_suspend(int index)
 {
-       int ret = -EOPNOTSUPP;
        int cpu = smp_processor_id();
 
-       if (cpuidle_ops[cpu].suspend)
-               ret = cpuidle_ops[cpu].suspend(index);
-
-       return ret;
+       return cpuidle_ops[cpu].suspend(index);
 }
 
 /**
@@ -92,8 +87,8 @@ static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
  * process.
  *
  * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
- * no cpuidle_ops is registered for the 'enable-method', or if no init callback
- * is defined.
+ * no cpuidle_ops is registered for the 'enable-method', or if either init or
+ * suspend callback isn't defined.
  */
 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
 {
@@ -111,8 +106,8 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
                return -EOPNOTSUPP;
        }
 
-       if (!ops->init) {
-               pr_warn("cpuidle_ops '%s': no init callback\n",
+       if (!ops->init || !ops->suspend) {
+               pr_warn("cpuidle_ops '%s': no init or suspend callback\n",
                        enable_method);
                return -EOPNOTSUPP;
        }