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
