BK72xx silicon requires a ~200us busy-wait (sctrl_dpll_delay200us) between
two watchdog register key writes on every reload, making each
arch_feed_wdt() call ~300us on BK7231T/N/BK7238. This is hardware errata
in the BDK's wdt_ctrl (beken378/driver/wdt/wdt.c:WCMD_RELOAD_PERIOD) and
cannot be worked around at the SDK level.
LibreTiny initialises the BK72xx HW watchdog at 10000ms, but ESPHome's
generic WDT_FEED_INTERVAL_MS of 300ms was sized for ESP8266's 1.6s soft
watchdog. That left BK72xx over-servicing the watchdog ~33x per timeout
window, paying ~60ms/min of main-loop overhead to no benefit.
Raise the interval to 2000ms on BK72xx only, which keeps a 5x safety
margin on the 10s HW WDT — matching the ESP8266 ratio that originally
motivated the 300ms value — while cutting feed frequency ~6x.
Measured on a NiceMCU XH-WB3S (BK7238) while testing
libretiny-eu/libretiny#360:
Before (300ms interval):
wdt_slow_path: hits=195 (5.9% of iters, avg=315.97us/hit)
main_loop_before_breakdown: sched=73.2ms, wdt=61.6ms, residual=0.0ms
Other platforms retain the existing 300ms value.
BDK 3.0.78 (required by LibreTiny for BK7238 support, see
libretiny-eu/libretiny#360) declares wifi_event_sta_disconnected_t in
wlan_defs_pub.h, which collides with the identically named typedef in
LibreTiny's Arduino WiFi API (WiFiEvents.h). Rename the BDK version
across the include so both headers can coexist. ESPHome only uses
bk_wlan_get_link_status from this header and doesn't reference the
renamed type.
The rename is a no-op on BDK 3.0.33 (BK7231T/N) since that version
doesn't declare the typedef.
The host platform's wake plumbing was split between wake.cpp (which had
wake_loop_threadsafe()) and application.{h,cpp} (which owned the fd
registry, wake socket lifecycle, select() loop, and readiness query).
The split required application.h to friend wake_loop_threadsafe() and
expose the wake socket fd, and forced a host-only out-of-line override
of yield_with_select_() that was equivalent to wakeable_delay() on every
other platform.
Consolidate the host wake mechanism in wake.h/wake.cpp:
- New host-only API: wake_register_fd, wake_unregister_fd, wake_fd_ready,
wake_setup, wake_drain_notifications.
- Host implementation of internal::wakeable_delay now performs the
select() over registered fds, mirroring the role of xTaskNotifyTake on
ESP32 and esp_delay on ESP8266.
- Application drops the host-specific socket_fds_, max_fd_,
wake_socket_fd_, socket_fds_changed_, read_fds_, base_read_fds_
members, the host include block (sys/select.h, sys/socket.h, etc.),
and the friend declarations for wake_loop_threadsafe() and
socket::socket_ready_fd().
- yield_with_select_() collapses to a single inline definition for all
platforms that delegates to wakeable_delay().
- Socket factories (bsd_sockets_impl.cpp, lwip_sockets_impl.cpp) and
socket::socket_ready_fd() now call the wake.h API directly instead of
going through App.
J. Nick Koston