It is not possible to generate 1 MHz REF_TICK from 2 MHz APB clock
(this is a limitation of REF_TICK divider circuit). Since switching
REF_TICK frequency is something we would like to avoid (to maintain
UART output even with DFS), 2 MHz frequency has been marked as
unsupported.
The issue would manifest itself in cases when switching from PM
configuration like {active=160MHz, idle=80MHz} to {active=80MHz,
idle=80Mhz}. After the configuration was changed, PM logic would
think that current frequency was 80MHz and would not do any further
switching. In fact, frequency was still 160MHz.
The old code calculated MAX() of two enum values, but CPU frequency
enum values are not ordered (2MHz goes after 240MHz). This caused
incorrect configuration to be set.
- separate mode stats from lock stats by an extra comment line
- add CPU frequency column to the mode stats
- don’t print a row for light sleep if light sleep is not enabled
s_cpu_freq_by_mode array was statically initialised with 80MHz CPU
frequency in CPU_MAX and APB_MAX modes, but sdkconfig setting for the
CPU frequency could have been different. For the case of 240MHz CPU
frequency, this would cause a frequency switch between 240MHz and
80MHz to happen, even though such switch is not supported in the fast
path switching functions used by the DFS implementation.
This fixes the issue by moving initialisation into esp_pm_impl_init,
which is called at startup before the first mode switch can happen.
Fixes https://github.com/espressif/esp-idf/issues/1729.
