Ethernet: Config by code instead KConfig (IDFGH-4761)

[petrkr]

Is possible initialize ethernet from code instead from KConfig how that was in IDF 3.x by some easy way than rewrite https://github.com/espressif/esp-idf/blob/v4.2/components/esp_eth/src/esp_eth_mac_esp32.c#L287 from scratch? Namely we need be able choose PHY, MDIO, MDC and CLOCK TYPE from code. It is not possible to maintain more binaries with hard-coded matrix. It's needed for micropython micropython/micropython#5265 (comment)

[igrr]

@petrkr The MDIO and MDC can be passed in eth_mac_config_t structure to esp_eth_mac_new_esp32:

esp-idf/examples/ethernet/basic/main/ethernet_example_main.c

Lines 88 to 89 in 0bbc721

	mac_config.smi_mdc_gpio_num = CONFIG_EXAMPLE_ETH_MDC_GPIO;
	mac_config.smi_mdio_gpio_num = CONFIG_EXAMPLE_ETH_MDIO_GPIO;

PHY can also be chosen by calling one of esp_eth_phy_new_* functions:

esp-idf/examples/ethernet/basic/main/ethernet_example_main.c

Line 92 in 0bbc721

esp_eth_phy_t *phy = esp_eth_phy_new_ip101(&phy_config);

.

The choice between clock modes is indeed compile-only at the moment. Agree that it makes sense to have it run-time configurable.