Since commit 94250e4, EXT0 wakeup mechanism, when wakeup level was set
to 0, started waking up chip immediately after entering deep sleep.
This failure was triggered in that commit by a change of
RTC_CNTL_MIN_SLP_VAL (i.e. minimum time in sleep mode until wakeup
can happen) from 128 cycles to 2 cycles.
The reason for this behaviour is related to the way input enable (IE)
signal going into an RTC pad is obtained:
PAD_IE = (SLP_SEL) ? SLP_IE & CHIP_SLEEP : IE,
where SLP_IE, SLP_SEL, and IE are bits of an RTC_IO register related
to the given pad. CHIP_SLEEP is the signal indicating that chip has
entered sleep mode.
The code in prepare_ext{0,1}_wakeup did not enable IE, but did enable
SLP_SEL and SLP_IE. This meant that until CHIP_SLEEP went high, PAD_IE
was 0, hence the input from the pad read 0 even if external signal
was 1. CHIP_SLEEP went high on the 2nd cycle of sleep. So when
RTC_CNTL_MIN_SLP_VAL was set to 2, the input signal from the pad was
latched as 0 at the moment when CHIP_SLEEP went high, causing EXT0
wakeup with level 0 to trigger.
This commit changes the way PAD_IE is enabled: SLP_SEL and SLP_IE are
no longer used, and IE is set to 1. If EXT0 wakeup is used, RTC_IO is
not powered down, so IE signal stays 1 both before CHIP_SLEEP goes
high and after. If EXT1 wakeup is used, RTC_IO may be powered down.
However prepare_ext1_wakeup enables Hold on the pad, locking states
of all the control signals, including IE.
Closes https://github.com/espressif/esp-idf/issues/1931
Closes https://github.com/espressif/esp-idf/issues/2043
4359d5985e