M1: Ethernet bring-up

net_eth module brings up the Waveshare ESP32-P4-ETH-POE Ethernet
interface (internal EMAC + IP101GRI PHY) and waits for a DHCP lease.

Pin map confirmed via Waveshare wiki + ESPHome's working config:
  MDC=31, MDIO=52, REF_CLK=50 (CLK_EXT_IN from PHY)
  TX_EN=49, TXD0=34, TXD1=35
  CRS_DV=28, RXD0=30, RXD1=29
  PHY reset/enable=51, PHY addr=1

app_main initializes NVS, netif, the default event loop, then starts
the Ethernet driver and waits up to 30s for an IP. On success it logs
the IP; on timeout it logs a warning and proceeds (the driver keeps
retrying in the background).

sdkconfig: declare 16 MB flash so partitions.csv (6.1 MB) fits.
main/CMakeLists.txt: explicit REQUIRES esp_eth esp_event esp_netif
nvs_flash.

Acceptance (per M1 in the impl guide): device gets a DHCP lease over
Ethernet and prints its IP. Build is clean against ESP-IDF 5.4 for
target esp32p4.

5 files changed, 201 insertions, 12 deletions

diff --git a/main/CMakeLists.txt b/main/CMakeLists.txt
index e088a07..ee5cb24 100644
--- a/main/CMakeLists.txt
+++ b/main/CMakeLists.txt
@@ -1,2 +1,5 @@
-idf_component_register(SRC_DIRS         "."
-                       INCLUDE_DIRS     ".")
+idf_component_register(
+    SRC_DIRS     "."
+    INCLUDE_DIRS "."
+    REQUIRES     esp_eth esp_event esp_netif nvs_flash
+)
diff --git a/main/app_main.c b/main/app_main.c
index 3c30497..8b91537 100644
--- a/main/app_main.c
+++ b/main/app_main.c
@@ -1,7 +1,9 @@
-#include <esp_log.h>
-#include <esp_event.h>
-#include <esp_netif.h>
-#include <nvs_flash.h>
+#include "net_eth.h"
+
+#include "esp_event.h"
+#include "esp_log.h"
+#include "esp_netif.h"
+#include "nvs_flash.h"
 
 static const char *TAG = "viewport";
 
@@ -13,10 +15,19 @@ void app_main(void)
 
     ESP_LOGI(TAG, "Scrypted Viewport boot");
 
-    // TODO: Ethernet (ESP32-P4 EMAC + Waveshare PoE PHY)
-    // TODO: mDNS _scrypted-viewport._tcp.local
-    // TODO: HTTP server: /state /config /frame
-    // TODO: MIPI-DSI panel init (800x480 IPS, default portrait 480x800)
-    // TODO: JPEG decode -> framebuffer
-    // TODO: Capacitive touch -> outbound /state POST
+    ESP_ERROR_CHECK(net_eth_init());
+    if (net_eth_wait_for_ip(30 * 1000) == ESP_OK) {
+        ESP_LOGI(TAG, "online at %s", net_eth_get_ip_str());
+    } else {
+        ESP_LOGW(TAG, "no DHCP lease after 30s, will keep retrying in the background");
+    }
+
+    // TODO M2: mDNS _scrypted-viewport._tcp.local
+    // TODO M2: HTTP server: GET /state
+    // TODO M3: MIPI-DSI panel init (800x480 IPS, default portrait 480x800)
+    // TODO M4: /config persistence (NVS)
+    // TODO M5: /frame JPEG decode -> framebuffer
+    // TODO M6: /state POST + idle timer
+    // TODO M7: Capacitive touch -> outbound /state POST
+    // TODO M8: Local screens (IP, loading) + BOOT button
 }
diff --git a/main/net_eth.c b/main/net_eth.c
new file mode 100644
index 0000000..640d880
--- /dev/null
+++ b/main/net_eth.c
@@ -0,0 +1,161 @@
+#include "net_eth.h"
+
+#include <string.h>
+
+#include "esp_check.h"
+#include "esp_eth.h"
+#include "esp_eth_mac.h"
+#include "esp_eth_phy.h"
+#include "esp_event.h"
+#include "esp_log.h"
+#include "esp_mac.h"
+#include "esp_netif.h"
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/event_groups.h"
+
+// Waveshare ESP32-P4-ETH-POE pin map. PHY is IP101GRI at MDIO addr 1.
+// REF_CLK is 50 MHz output from the PHY into GPIO50 (CLK_EXT_IN).
+// Verified against Waveshare wiki and ESPHome's working config.
+#define PIN_PHY_MDC         31
+#define PIN_PHY_MDIO        52
+#define PIN_PHY_REF_CLK     50
+#define PIN_PHY_TX_EN       49
+#define PIN_PHY_TXD0        34
+#define PIN_PHY_TXD1        35
+#define PIN_PHY_CRS_DV      28
+#define PIN_PHY_RXD0        30
+#define PIN_PHY_RXD1        29
+#define PIN_PHY_RESET       51
+#define PHY_ADDR            1
+
+static const char *TAG = "net_eth";
+
+static EventGroupHandle_t s_event_group;
+static const int BIT_GOT_IP = BIT0;
+
+static esp_netif_t *s_eth_netif;
+static esp_eth_handle_t s_eth_handle;
+static char s_ip_str[16] = {0};
+
+static void on_eth_event(void *arg, esp_event_base_t event_base,
+                         int32_t event_id, void *event_data)
+{
+    uint8_t mac[6] = {0};
+    esp_eth_handle_t handle = *(esp_eth_handle_t *)event_data;
+
+    switch (event_id) {
+    case ETHERNET_EVENT_CONNECTED:
+        esp_eth_ioctl(handle, ETH_CMD_G_MAC_ADDR, mac);
+        ESP_LOGI(TAG, "link up, mac %02x:%02x:%02x:%02x:%02x:%02x",
+                 mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+        break;
+    case ETHERNET_EVENT_DISCONNECTED:
+        ESP_LOGW(TAG, "link down");
+        xEventGroupClearBits(s_event_group, BIT_GOT_IP);
+        break;
+    case ETHERNET_EVENT_START:
+        ESP_LOGI(TAG, "ethernet started");
+        break;
+    case ETHERNET_EVENT_STOP:
+        ESP_LOGI(TAG, "ethernet stopped");
+        break;
+    default:
+        break;
+    }
+}
+
+static void on_ip_event(void *arg, esp_event_base_t event_base,
+                        int32_t event_id, void *event_data)
+{
+    ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
+    const esp_netif_ip_info_t *ip = &event->ip_info;
+
+    snprintf(s_ip_str, sizeof(s_ip_str), IPSTR, IP2STR(&ip->ip));
+    ESP_LOGI(TAG, "got ip %s  gw " IPSTR "  netmask " IPSTR,
+             s_ip_str, IP2STR(&ip->gw), IP2STR(&ip->netmask));
+
+    xEventGroupSetBits(s_event_group, BIT_GOT_IP);
+}
+
+esp_err_t net_eth_init(void)
+{
+    s_event_group = xEventGroupCreate();
+    if (!s_event_group) return ESP_ERR_NO_MEM;
+
+    esp_netif_inherent_config_t base_cfg = ESP_NETIF_INHERENT_DEFAULT_ETH();
+    esp_netif_config_t netif_cfg = {
+        .base = &base_cfg,
+        .stack = ESP_NETIF_NETSTACK_DEFAULT_ETH,
+    };
+    s_eth_netif = esp_netif_new(&netif_cfg);
+    if (!s_eth_netif) return ESP_FAIL;
+
+    eth_mac_config_t mac_config = ETH_MAC_DEFAULT_CONFIG();
+    eth_esp32_emac_config_t emac_config = ETH_ESP32_EMAC_DEFAULT_CONFIG();
+    emac_config.smi_gpio.mdc_num  = PIN_PHY_MDC;
+    emac_config.smi_gpio.mdio_num = PIN_PHY_MDIO;
+    emac_config.clock_config.rmii.clock_mode = EMAC_CLK_EXT_IN;
+    emac_config.clock_config.rmii.clock_gpio = PIN_PHY_REF_CLK;
+    // ESP32-P4 EMAC also needs the data pins routed explicitly.
+    emac_config.emac_dataif_gpio.rmii.tx_en_num = PIN_PHY_TX_EN;
+    emac_config.emac_dataif_gpio.rmii.txd0_num  = PIN_PHY_TXD0;
+    emac_config.emac_dataif_gpio.rmii.txd1_num  = PIN_PHY_TXD1;
+    emac_config.emac_dataif_gpio.rmii.crs_dv_num = PIN_PHY_CRS_DV;
+    emac_config.emac_dataif_gpio.rmii.rxd0_num  = PIN_PHY_RXD0;
+    emac_config.emac_dataif_gpio.rmii.rxd1_num  = PIN_PHY_RXD1;
+    emac_config.interface = EMAC_DATA_INTERFACE_RMII;
+
+    esp_eth_mac_t *mac = esp_eth_mac_new_esp32(&emac_config, &mac_config);
+    if (!mac) {
+        ESP_LOGE(TAG, "esp_eth_mac_new_esp32 failed");
+        return ESP_FAIL;
+    }
+
+    eth_phy_config_t phy_config = ETH_PHY_DEFAULT_CONFIG();
+    phy_config.phy_addr = PHY_ADDR;
+    phy_config.reset_gpio_num = PIN_PHY_RESET;
+    esp_eth_phy_t *phy = esp_eth_phy_new_ip101(&phy_config);
+    if (!phy) {
+        ESP_LOGE(TAG, "esp_eth_phy_new_ip101 failed");
+        return ESP_FAIL;
+    }
+
+    esp_eth_config_t eth_config = ETH_DEFAULT_CONFIG(mac, phy);
+    ESP_RETURN_ON_ERROR(esp_eth_driver_install(&eth_config, &s_eth_handle),
+                       TAG, "driver install failed");
+
+    ESP_RETURN_ON_ERROR(esp_netif_attach(s_eth_netif,
+                                        esp_eth_new_netif_glue(s_eth_handle)),
+                       TAG, "netif attach failed");
+
+    ESP_RETURN_ON_ERROR(esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID,
+                                                  on_eth_event, NULL),
+                       TAG, "eth event register failed");
+    ESP_RETURN_ON_ERROR(esp_event_handler_register(IP_EVENT, IP_EVENT_ETH_GOT_IP,
+                                                  on_ip_event, NULL),
+                       TAG, "ip event register failed");
+
+    ESP_RETURN_ON_ERROR(esp_eth_start(s_eth_handle), TAG, "eth start failed");
+    ESP_LOGI(TAG, "ethernet driver started, waiting for link + DHCP");
+    return ESP_OK;
+}
+
+esp_err_t net_eth_wait_for_ip(uint32_t timeout_ms)
+{
+    TickType_t ticks = timeout_ms == UINT32_MAX ? portMAX_DELAY
+                                                : pdMS_TO_TICKS(timeout_ms);
+    EventBits_t bits = xEventGroupWaitBits(s_event_group, BIT_GOT_IP,
+                                           pdFALSE, pdTRUE, ticks);
+    return (bits & BIT_GOT_IP) ? ESP_OK : ESP_ERR_TIMEOUT;
+}
+
+bool net_eth_is_up(void)
+{
+    return (xEventGroupGetBits(s_event_group) & BIT_GOT_IP) != 0;
+}
+
+const char *net_eth_get_ip_str(void)
+{
+    return s_ip_str;
+}
diff --git a/main/net_eth.h b/main/net_eth.h
new file mode 100644
index 0000000..23f2450
--- /dev/null
+++ b/main/net_eth.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "esp_err.h"
+
+esp_err_t net_eth_init(void);
+esp_err_t net_eth_wait_for_ip(uint32_t timeout_ms);
+bool net_eth_is_up(void);
+const char *net_eth_get_ip_str(void);
diff --git a/sdkconfig.defaults b/sdkconfig.defaults
index 3f88f72..e612dc8 100644
--- a/sdkconfig.defaults
+++ b/sdkconfig.defaults
@@ -1,5 +1,9 @@
 CONFIG_IDF_TARGET="esp32p4"
 
+# Flash (Waveshare ESP32-P4-ETH-POE ships with 16 MB QSPI flash)
+CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
+CONFIG_ESPTOOLPY_FLASHSIZE="16MB"
+
 # Partition table
 CONFIG_PARTITION_TABLE_CUSTOM=y
 CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions.csv"