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

Daniel Lezcano
2015-03-19T17:11:21Z

On 03/19/2015 04:42 PM, Lina Iyer wrote:
> On Thu, Mar 19 2015 at 09:33 -0600, Daniel Lezcano wrote:
>> 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@linaro.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.
>>
>
> But this is static pointer, I can see that struct cpuidle_device * being
> used by cpuidle framework.
>
> It gets stored here?
>
> DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
>
> But we dont need to save it here, for in this file, there is no per-cpu
> access, other than when the registration fails.

Indeed, that is true. There is no need of these cpuidle variables.
Furthermore, we can access the cpuidle_devices directly as they are
exported in cpuidle.h.

I will fix it.

Thanks
-- Daniel

>>>> +
>>>> /*
>>>> * 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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