esp-idf/components/esp_eth/Kconfig

menu "Ethernet"

    menuconfig ETH_USE_ESP32_EMAC
        depends on IDF_TARGET_ESP32
        bool "Support ESP32 internal EMAC controller"
        default y
        help
            ESP32 integrates a 10/100M Ethernet MAC controller.

    if ETH_USE_ESP32_EMAC
        choice ETH_PHY_INTERFACE
            prompt "PHY interface"
            default ETH_PHY_INTERFACE_RMII
            help
                Select the communication interface between MAC and PHY chip.

            config ETH_PHY_INTERFACE_RMII
                bool "Reduced Media Independent Interface (RMII)"

            config ETH_PHY_INTERFACE_MII
                bool "Media Independent Interface (MII)"
        endchoice

        if ETH_PHY_INTERFACE_RMII
            choice ETH_RMII_CLK_MODE
                prompt "RMII clock mode"
                default ETH_RMII_CLK_INPUT
                help
                    Select external or internal RMII clock.

                config ETH_RMII_CLK_INPUT
                    bool "Input RMII clock from external"
                    help
                        MAC will get RMII clock from outside.
                        Note that ESP32 only supports GPIO0 to input the RMII clock.

                config ETH_RMII_CLK_OUTPUT
                    bool "Output RMII clock from internal"
                    help
                        ESP32 can generate RMII clock by internal APLL.
                        This clock can be routed to the external PHY device.
                        ESP32 supports to route the RMII clock to GPIO0/16/17.
            endchoice
        endif

        if ETH_RMII_CLK_INPUT
            config ETH_RMII_CLK_IN_GPIO
                int
                range 0 0
                default 0
                help
                    ESP32 only supports GPIO0 to input the RMII clock.
        endif

        if ETH_RMII_CLK_OUTPUT
            config ETH_RMII_CLK_OUTPUT_GPIO0
                bool "Output RMII clock from GPIO0 (Experimental!)"
                default n
                help
                    GPIO0 can be set to output a pre-divided PLL clock (test only!).
                    Enabling this option will configure GPIO0 to output a 50MHz clock.
                    In fact this clock doesn't have directly relationship with EMAC peripheral.
                    Sometimes this clock won't work well with your PHY chip. You might need to
                    add some extra devices after GPIO0 (e.g. inverter).
                    Note that outputting RMII clock on GPIO0 is an experimental practice.
                    If you want the Ethernet to work with WiFi, don't select GPIO0 output mode for stability.

            if !ETH_RMII_CLK_OUTPUT_GPIO0
                config ETH_RMII_CLK_OUT_GPIO
                    int "RMII clock GPIO number"
                    range 16 17
                    default 17
                    help
                        Set the GPIO number to output RMII Clock.
            endif
        endif

        config ETH_DMA_BUFFER_SIZE
            int "Ethernet DMA buffer size (Byte)"
            range 256 1600
            default 512
            help
                Set the size of each buffer used by Ethernet MAC DMA.

        config ETH_DMA_RX_BUFFER_NUM
            int "Amount of Ethernet DMA Rx buffers"
            range 3 30
            default 10
            help
                Number of DMA receive buffers. Each buffer's size is ETH_DMA_BUFFER_SIZE.
                Larger number of buffers could increase throughput somehow.

        config ETH_DMA_TX_BUFFER_NUM
            int "Amount of Ethernet DMA Tx buffers"
            range 3 30
            default 10
            help
                Number of DMA transmit buffers. Each buffer's size is ETH_DMA_BUFFER_SIZE.
                Larger number of buffers could increase throughput somehow.
    endif

    menuconfig ETH_USE_SPI_ETHERNET
        bool "Support SPI to Ethernet Module"
        default y
        help
            ESP-IDF can also support some SPI-Ethernet module.

    if ETH_USE_SPI_ETHERNET
        config ETH_SPI_ETHERNET_DM9051
            bool "Use DM9051"
            default y
            help
                DM9051 is a fast Ethernet controller with an SPI interface.
                It's also integrated with a 10/100M PHY and MAC.
                Set true to enable DM9051 driver.
    endif
endmenu