[realtek-amb] Use Wi-Fi partial scan to fix delays, add watchdog resets

[bdraco]

Fix WiFi connection delays and watchdog resets on Realtek

Some users have been experiencing watchdog resets during WiFi connection. After investigating, found that wifi_connect_bssid() was scanning all channels even when we already know the target channel from the prior scan.

Changes

• Use wifi_set_pscan_chan() to limit the SDK's internal scan to just the target channel when known
• Add watchdog feeds before/after the blocking connect and DHCP calls

Before/After

Connect time dropped from ~2.8s to ~1.5s, total blocking from ~4s to ~2s. The watchdog feeds ensure no single blocking period exceeds ~1.5s.

[bdraco]

before
[15:22:58.657]Interface 0 IP address : 192.168.107.178[W][component:546]: wifi took a long time for an operation (3785 ms)
after

[16:08:30.286]Interface 0 IP address : 192.168.107.178[W][component:546]: wifi took a long time for an operation (2686 ms)

Lot better now and no watchdog resets on the bad case

[bdraco]

just need to boot it off the wifi and make sure it can still scan

[bdraco]

all good, reconnects to a different bssid when I reboot the ap

[bdraco]

looks like we have a bug in ESPHome on scan after forced disconnect 🙈

[bdraco]

reconnect scan bug in esphome fixed as well esphome/esphome#13514

[kuba2k2]

The realtek-amb core is used on both RTL8720C and RTL8710B. I'll need to first check if it at least compiles on BN, since IIRC you're only able to test on BW15 (CF).

[bdraco]

compiles ok with

esphome:
  name: wr2-test
  friendly_name: WR2 Test

rtl87xx:
  board: wr2
  framework:
    version: 1.10.0
    source: /Users/bdraco/libretiny

logger:
  level: VERBOSE

api:

ota:
  - platform: esphome

debug:
  update_interval: 5s

sensor:
  - platform: debug
    free:
      name: "Free Heap"
    min_free:
      name: "Min Free Heap"
    loop_time:
      name: "Loop Time"

text_sensor:
  - platform: debug
    reset_reason:
      name: "Reset Reason"

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  ap:

But don't have the hardware to validate on