bsp_p4_eye_init()` resets ESP32-C6 coprocessor via `rtc_gpio_init(BSP_C6_EN_PIN) (AEGHB-1252)

[AlverGant]

Hi, I was having difficulties using UART communication between P4 and C6 with my custom firmware and after some debugging I initially suspected DMA interference or electrical noise from XCLK, but testing confirmed the issue is purely software-related (RTC GPIO reconfiguration).

Environment

• Development Kit: (ESP32-P4-EYE)
• ESP-IDF Version: v5.5.1
• BSP Version: espressif/esp32_p4_eye from esp-dev-kits (commit 602c810)
• Affected Component: bsp_p4_eye_init() in esp32_p4_eye.c
• Hardware Setup:
  • ESP32-P4 (main processor)
  • ESP32-C6 (coprocessor for WiFi/Bluetooth communication via UART2)

Problem Description

When using the ESP32-P4-EYE board with an ESP32-C6 coprocessor communicating via UART, calling bsp_p4_eye_init() resets the C6, breaking UART communication.

The issue is caused by this line in esp32_p4_eye.c:368:

rtc_gpio_init(BSP_C6_EN_PIN);  // GPIO 9

This reconfigures the C6's enable pin (GPIO 9), causing the C6 to reset and lose its initialized state (WiFi connection, network stack, etc.).

Impact

This affects any application that:

1. Uses the BSP (bsp_p4_eye_init()) to initialize the board
2. Relies on ESP32-C6 coprocessor for network connectivity
3. Needs the C6 to remain running after P4 initialization

Symptoms:

• C6 stops responding to UART commands after bsp_p4_eye_init()
• UART communication works perfectly in isolated tests
• C6 must be re-initialized after P4 BSP init, losing connection state

Steps to Reproduce

1. Setup: Connect ESP32-C6 to ESP32-P4 via UART2 (TX: GPIO35, RX: GPIO36)
2. C6 Firmware: Initialize WiFi and wait for connection
3. P4 Firmware:
   • Wait for C6 to signal ready (e.g., "C6_READY" via UART)
   • Call bsp_p4_eye_init()
4. Observe: C6 stops responding, UART communication fails

[Horion0415]

This could indeed be an issue. That function is intended for low-power scenarios, so the C6 EN pin can still be pulled low during sleep. I may add a configuration option to manage this pin in the future.