esp_idf_sys

Constant esp_flash_io_mode_t_SPI_FLASH_READ_MODE_MAX

Source 
pub const esp_flash_io_mode_t_SPI_FLASH_READ_MODE_MAX: esp_flash_io_mode_t = 18;
Expand description

< The fastest io mode supported by the host is ESP_FLASH_READ_MODE_MAX-1.