From mboxrd@z Thu Jan 1 00:00:00 1970 From: jszhang@marvell.com (Jisheng Zhang) Date: Thu, 31 Mar 2016 17:31:07 +0800 Subject: [PATCH v3 2/2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient In-Reply-To: <1459416667-307-1-git-send-email-jszhang@marvell.com> References: <1459416667-307-1-git-send-email-jszhang@marvell.com> Message-ID: <1459416667-307-3-git-send-email-jszhang@marvell.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 --- arch/arm/kernel/cpuidle.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c index 18b5a73..c4280e3 100644 --- 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 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; } -- 2.8.0.rc3