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

[Greentime Hu]

2017-11-17 20:50 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx>:
> On Fri, Nov 17, 2017 at 1:39 PM, Greentime Hu <green.hu@xxxxxxxxx> wrote:
>> 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
>
> You will have to provide an architecture-specific implementation of
> this function, please ahve a look at what others are doing, e.g. tile,
> openrisc or
> h8300.

Thanks. I got you.