Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758728AbcC3Hw0 (ORCPT ); Wed, 30 Mar 2016 03:52:26 -0400 Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:50365 "EHLO mx0a-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754891AbcC3HwZ (ORCPT ); Wed, 30 Mar 2016 03:52:25 -0400 From: Jisheng Zhang To: , , CC: , , , Jisheng Zhang Subject: [PATCH v2] ARM: cpuidle: make arm_cpuidle_suspend() a bit more efficient Date: Wed, 30 Mar 2016 15:47:57 +0800 Message-ID: <1459324077-7116-1-git-send-email-jszhang@marvell.com> X-Mailer: git-send-email 2.8.0.rc3 MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-03-30_04:,, signatures=0 X-Proofpoint-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1601100000 definitions=main-1603300114 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2733 Lines: 77 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 --- Since v1: - drop patch1, I.E "ARM: cpuidle: fix !cpuidle_ops[cpu].init case during init", because there may be platforms which doesn't need the init member at all. - adopt Daniel's suggestion to move the cpuidle_ops.suspend check to arm_cpuidle_read_ops(). arch/arm/kernel/cpuidle.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/arch/arm/kernel/cpuidle.c b/arch/arm/kernel/cpuidle.c index 703926e..e63388e 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); } /** @@ -92,7 +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'. + * no cpuidle_ops is registered for the 'enable-method', or if no suspend + * callback is defined. */ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) { @@ -110,6 +106,12 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) return -EOPNOTSUPP; } + if (!ops->suspend) { + pr_warn("cpuidle_ops '%s': no suspend callback\n", + enable_method); + return -EOPNOTSUPP; + } + cpuidle_ops[cpu] = *ops; /* structure copy */ pr_notice("cpuidle: enable-method property '%s'" @@ -129,7 +131,8 @@ static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu) * Returns: * 0 on success, * -ENODEV if it fails to find the cpu node in the device tree, - * -EOPNOTSUPP if it does not find a registered cpuidle_ops for this cpu, + * -EOPNOTSUPP if it does not find a registered and valid cpuidle_ops for + * this cpu, * -ENOENT if it fails to find an 'enable-method' property, * -ENXIO if the HW reports a failure or a misconfiguration, * -ENOMEM if the HW report an memory allocation failure -- 2.8.0.rc3