Clarification on the HW RNG (IDFGH-13813)

[KaeLL]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

Chip: Vanilla ESP32

Docs say

The hardware RNG produces true random numbers under any of the following conditions:
RF subsystem is enabled (i.e., Wi-Fi or Bluetooth are enabled).

and the TRM says

High-speed ADC is enabled automatically when the Wi-Fi or Bluetooth modules is enabled.

"module/subsystem is enabled". When exactly is that? And up until when exactly? (As in, after and until X and Y function calls, etc).
More specifically, I need to know if by the time nimBLE on_sync cb gets called, esp_random is already a TNRG.

Also, from the TRM

when the Wi-Fi module is enabled, the value read from the high-speed ADC can be saturated in some extreme cases

Such as? Answers to these questions are likely worth adding to the docs.