esp-idf/components/esp_eth/Kconfig

menu "Ethernet"

    # Invisible item that is enabled if any Ethernet selection is made
    config ETH_ENABLED
        bool

    menuconfig ETH_USE_ESP32_EMAC
        depends on IDF_TARGET_ESP32
        bool "Support ESP32 internal EMAC controller"
        default y
        select ETH_ENABLED
        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)"
        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 # ETH_PHY_INTERFACE_RMII

        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 # ETH_RMII_CLK_INPUT

        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 # !ETH_RMII_CLK_OUTPUT_GPIO0
        endif # ETH_RMII_CLK_OUTPUT

        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.

        if ETH_DMA_RX_BUFFER_NUM > 15
            config ETH_SOFT_FLOW_CONTROL
                bool "Enable software flow control"
                default n
                help
                    Ethernet MAC engine on ESP32 doesn't feature a flow control logic.
                    The MAC driver can perform a software flow control if you enable this option.
                    Note that, if the RX buffer number is small, enabling software flow control will
                    cause obvious performance loss.
        endif

        config ETH_IRAM_OPTIMIZATION
            bool "Enable IRAM optimization"
            default n
            help
                If enabled, functions related to RX/TX are placed into IRAM. It can improve Ethernet throughput.
                If disabled, all functions are placed into FLASH.

    endif # ETH_USE_ESP32_EMAC

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

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

        config ETH_SPI_ETHERNET_W5500
            bool "Use W5500 (MAC RAW)"
            help
                W5500 is a HW TCP/IP embedded Ethernet controller.
                TCP/IP stack, 10/100 Ethernet MAC and PHY are embedded in a single chip.
                However the driver in ESP-IDF only enables the RAW MAC mode,
                making it compatible with the software TCP/IP stack.
                Say yes to enable W5500 driver.

        config ETH_SPI_ETHERNET_KSZ8851SNL
            bool "Use KSZ8851SNL"
            help
                The KSZ8851SNL is a single-chip Fast Ethernet controller consisting of
                a 10/100 physical layer transceiver (PHY), a MAC, and a Serial Peripheral Interface (SPI).
                Select this to enable KSZ8851SNL driver.
    endif # ETH_USE_SPI_ETHERNET

    menuconfig ETH_USE_OPENETH
        bool "Support OpenCores Ethernet MAC (for use with QEMU)"
        default n
        select ETH_ENABLED
        help
            OpenCores Ethernet MAC driver can be used when an ESP-IDF application
            is executed in QEMU. This driver is not supported when running on a
            real chip.

    if ETH_USE_OPENETH
        config ETH_OPENETH_DMA_RX_BUFFER_NUM
            int "Number of Ethernet DMA Rx buffers"
            range 1 64
            default 4
            help
                Number of DMA receive buffers, each buffer is 1600 bytes.

        config ETH_OPENETH_DMA_TX_BUFFER_NUM
            int "Number of Ethernet DMA Tx buffers"
            range 1 64
            default 1
            help
                Number of DMA transmit buffers, each buffer is 1600 bytes.
    endif # ETH_USE_OPENETH

    config ETH_TRANSMIT_MUTEX
        depends on ETH_ENABLED
        bool "Enable Transmit Mutex"
        default n
        help
            Prevents multiple accesses when Ethernet interface is used as shared resource and multiple
            functionalities might try to access it at a time.
endmenu