Re: [PATCH V2 7/8] ARM: cpuidle: Register per cpuidle device

Daniel Lezcano
2015-03-19T15:33:16Z

On 03/19/2015 04:31 PM, Lina Iyer wrote:
> On Wed, Mar 18 2015 at 12:46 -0600, Daniel Lezcano wrote:
>> Some architectures have some cpus which does not support idle states.
>>
>> Let the underlying low level code to return -ENOSYS when it is not
>> possible to set an idle state.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>> ---
>> drivers/cpuidle/cpuidle-arm.c | 45
>> +++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 43 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-arm.c
>> b/drivers/cpuidle/cpuidle-arm.c
>> index 1c94b88..0682ed0 100644
>> --- a/drivers/cpuidle/cpuidle-arm.c
>> +++ b/drivers/cpuidle/cpuidle-arm.c
>> @@ -17,11 +17,14 @@
>> #include <linux/kernel.h>
>> #include <linux/module.h>
>> #include <linux/of.h>
>> +#include <linux/slab.h>
>>
>> #include <asm/cpuidle.h>
>>
>> #include "dt_idle_states.h"
>>
>> +static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
>
> Is a per-cpu variable needed? There seems to be no per-cpu access, other
> than at init.

:)

Actually it is the cpuidle framework which is using the per cpu variable.

>> +
>> /*
>> * arm_enter_idle_state - Programs CPU to enter the specified state
>> *
>> @@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
>> {
>> int cpu, ret;
>> struct cpuidle_driver *drv = &arm_idle_driver;
>> + struct cpuidle_device *dev;
>>
>> /*
>> * Initialize idle states data, starting at index 1.
>> @@ -105,18 +109,55 @@ static int __init arm_idle_init(void)
>> if (ret <= 0)
>> return ret ? : -ENODEV;
>>
>> + ret = cpuidle_register_driver(drv);
>> + if (ret) {
>> + pr_err("Failed to register cpuidle driver\n");
>> + return ret;
>> + }
>> +
>> /*
>> * Call arch CPU operations in order to initialize
>> * idle states suspend back-end specific data
>> */
>> for_each_possible_cpu(cpu) {
>> ret = arm_cpuidle_init(cpu);
>> +
>> + /* This cpu does not support any idle states */
>> + if (ret == -ENOSYS)
>> + continue;
>> +
>> if (ret) {
>> pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>> - return ret;
>> + goto out_fail;
>> + }
>> +
>> + dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>> + if (!dev) {
>> + pr_err("Failed to allocate cpuidle device\n");
>> + goto out_fail;
>> + }
>> +
>> + dev->cpu = cpu;
>> + per_cpu(cpuidle_arm_dev, cpu) = dev;
>> +
>> + ret = cpuidle_register_device(dev);
>> + if (ret) {
>> + pr_err("Failed to register cpuidle device for CPU %d\n",
>> + cpu);
>> + kfree(dev);
>> + goto out_fail;
>> }
>> }
>> +out:
>> + return ret;
>>
>> - return cpuidle_register(drv, NULL);
>> +out_fail:
>> + for (cpu--; cpu <= 0; cpu--) {
>> + dev = per_cpu(cpuidle_arm_dev, cpu);
>> + cpuidle_unregister_device(dev);
>> + kfree(dev);
>> + }
>> + cpuidle_unregister_driver(drv);
>> + goto out;
>> }
>> device_initcall(arm_idle_init);
>> --
>> 1.9.1
>>

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