On 14/02/2022 03:55, Edwin Chiu 邱垂峰 wrote:
> Hi Krzysztof:
>
> Please see below answer.
>
>>> +static struct cpuidle_driver sp7021_idle_driver = {
>>> + .name = "sp7021_idle",
>>> + .owner = THIS_MODULE,
>>> + /*
>>> + * State at index 0 is standby wfi and considered standard
>>> + * on all ARM platforms. If in some platforms simple wfi
>>> + * can't be used as "state 0", DT bindings must be implemented
>>> + * to work around this issue and allow installing a special
>>> + * handler for idle state index 0.
>>> + */
>>> + .states[0] = {
>>> + .enter = sp7021_enter_idle_state,
>>> + .exit_latency = 1,
>>> + .target_residency = 1,
>>> + .power_usage = UINT_MAX,
>>> + .name = "WFI",
>>> + .desc = "ARM WFI",
>>
>> I have impression that there is no point in having custom driver with WFI...
>>
>> Still the main question from Daniel and Sudeep stays: why do you need this? You copied exactly
>> cpuildle-arm driver, there is nothing different here. At least I could not spot differences. Maybe except
>> that you use cpu_v7_do_idle explicitly.
>>
>> Unfortunately I cannot understand the explanation here:
>> https://lore.kernel.org/all/0812c44f777d4026b79df2e3698294be@xxxxxxxxxxxxxxxxxxxxxxxx/
>> Why exactly cpuidle-arm does not work in your case?
>>
> Edwin=> I mean cpuidle-arm driver can't directly use with no modified.
> If someone want to use cpuidle-arm driver, below modification seems necessary.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Static int sp7021_cpuidle_suspend_enter(unsigned long index) {~}
> Static int __init sp7021_cpuidle_init(struct device_node *cpu_node, int cpu) {~}
> Static const struct cpuidle_ops sc_smp_ops __initconst = {
> .suspend = sp7021_cpuidle_suspend_enter,
> .init = sp7021_cpuidle_init,
> };
> CPUIDLE_METHOD_OF_DECLARE(sc_smp, "sunplus,sc-smp", &sc_smp_ops); //declare enable method
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> But change cpuilde-arm.c for sunplus driver seems not reasonable.
> That is why I want to submit cpuidle-sunplus.c
> Althought sunplus cpuidle only come in WFI, but it can complete the cpuidle framework.
I don't think it is correct. You can use cpuidle-arm, because it is
being always initialized with device_initcall(). You either use
appropriate compatible in DT or add your compatible to cpuidle-arm.
Even if this did not work, then the solution is to use common parts, not
to duplicate entire driver. Duplicating is not acceptable.
Best regards,
Krzysztof
