rtc_clk_cal() call returns 0 after watchdog reboot

[MindReader32]

Hi,

I raised an issue against an audio library, the original issue with detail can be found here: https://github.com/earlephilhower/ESP82 ... issues/399

Occurs on both 1.0.4 and 1.0.6 and the latest 2.x alpha Arduino libraries.

The fundamental problem is that after a watchdog reset the `rtc_clk_cal` function always returns 0.

I've tried repeatedly calling it until it returns non-0 but after such a watchdog reset it never does.

Any help would be appreciated,
Thanks
Wayne