esp-idf/components/esp_driver_spi/Kconfig

menu "ESP-Driver:SPI Configurations"
    depends on SOC_GPSPI_SUPPORTED
    config SPI_MASTER_IN_IRAM
        bool "Place transmitting functions of SPI master into IRAM"
        default n
        depends on !FREERTOS_PLACE_FUNCTIONS_INTO_FLASH
        select SPI_MASTER_ISR_IN_IRAM
        help
            Normally only the ISR of SPI master is placed in the IRAM, so that it
            can work without the flash when interrupt is triggered.
            For other functions, there's some possibility that the flash cache
            miss when running inside and out of SPI functions, which may increase
            the interval of SPI transactions.
            Enable this to put ``queue_trans``, ``get_trans_result`` and
            ``transmit`` functions into the IRAM to avoid possible cache miss.

            This configuration won't be available if `CONFIG_FREERTOS_PLACE_FUNCTIONS_INTO_FLASH` is enabled.

            During unit test, this is enabled to measure the ideal case of api.

    config SPI_MASTER_ISR_IN_IRAM
        bool "Place SPI master ISR function into IRAM"
        default y
        depends on !HEAP_PLACE_FUNCTION_INTO_FLASH
        select PERIPH_CTRL_FUNC_IN_IRAM
        select HAL_SPI_MASTER_FUNC_IN_IRAM
        help
            Place the SPI master ISR in to IRAM to avoid possible cache miss.

            Enabling this configuration is possible only when HEAP_PLACE_FUNCTION_INTO_FLASH
            is disabled since the spi master uses can allocate transactions buffers into DMA
            memory section using the heap component API that ipso facto has to be placed in IRAM.

            Also you can forbid the ISR being disabled during flash writing
            access, by add ESP_INTR_FLAG_IRAM when initializing the driver.

    config SPI_SLAVE_IN_IRAM
        bool "Place transmitting functions of SPI slave into IRAM"
        default n
        select SPI_SLAVE_ISR_IN_IRAM
        help
            Normally only the ISR of SPI slave is placed in the IRAM, so that it
            can work without the flash when interrupt is triggered.
            For other functions, there's some possibility that the flash cache
            miss when running inside and out of SPI functions, which may increase
            the interval of SPI transactions.
            Enable this to put ``queue_trans``, ``get_trans_result`` and
            ``transmit`` functions into the IRAM to avoid possible cache miss.

    config SPI_SLAVE_ISR_IN_IRAM
        bool "Place SPI slave ISR function into IRAM"
        default y
        select PERIPH_CTRL_FUNC_IN_IRAM
        select HAL_SPI_SLAVE_FUNC_IN_IRAM
        help
            Place the SPI slave ISR in to IRAM to avoid possible cache miss.

            Also you can forbid the ISR being disabled during flash writing
            access, by add ESP_INTR_FLAG_IRAM when initializing the driver.

endmenu # SPI Configuration