Re: [PATCH 26/31] nds32: Build infrastructure

[Greentime Hu]

2017-11-10 16:26 GMT+08:00 Greentime Hu <green.hu@xxxxxxxxx>:
> 2017-11-09 18:33 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>:
>> On Thu, Nov 9, 2017 at 10:02 AM, Greentime Hu <green.hu@xxxxxxxxx> wrote:
>>> 2017-11-08 18:16 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>:
>>>> On Wed, Nov 8, 2017 at 6:55 AM, Greentime Hu <green.hu@xxxxxxxxx> wrote:
>>
>>>>> +config GENERIC_CALIBRATE_DELAY
>>>>> +       def_bool y
>>>>
>>>> It's better to avoid the delay loop completely and skip the calibration,
>>>> if your hardware allows.
>>>
>>> Thanks.
>>> Do you mean that this config should be def_bool n?
>>> why? Almost all arch enable it.
>>
>> It depends on what your hardware can do. If you have a way to see how much
>> time has passed that is guaranteed to be reliable on all machines, then
>> use that instead.
>>
>> On a lot of architectures, it's not possible, so they have to fall back to using
>> the delay loop.
>
> I get it. I will discuss it with our HW colleagues.
> We may get these informations in some registers.

Hi, Arnd:

I think I can't set it to default n because it will be called in start_kernel.

start_kernel() -> calibrate_delay()

If I don't enable this config, it will link error because it didn't
build init/calibrate.c