In the adi_rom_Boot() API, there's an option called Automatic device detection (ROM_BCMD_SPIM_NOAUTO).
When set to zero, the API automatically detects the device and configures the peripheral based on the BCODE value (first nibble) of the boot stream block header. This means the clock configuration depends on the BCODE value of the loader file (Secondary application).
If set to 1, automatic device detection is disabled, and the settings provided in other fields of this register are used to configure the boot mode. This implies that each boot command configuration needs to be manually set. The SPI clock will be configured based on the ROM_BCMD_SPIM_SPEED bit field instead of the BCODE.
For instance:
When ROM_BCMD_SPIM_NOAUTO is 0 and Secondary Loader file is created with BCODE 1, then Baud rate is 0xF.
When ROM_BCMD_SPIM_NOAUTO is 1, can customize the baud rate further by using ROM_BCMD_SPIM_SPEED bit, which can configure between 0 to 15.