Setup UART clock to get maximum baud rate

Dear @stefan_e.tx ,

I spoke about 80 MHz since in the IMX7DRM document at chapter 5.2 Clock Control Module the UART1_CLK_ROOT must have a maximum clock frequency of 80 MHz.
1825-clock.jpg

However, 4 Mbps is good for my tests.
I would like to test the maximum baud rate and understand if eventually evaluate an external SPI/I2C - UART chip for our custom carrier board.

How can I setup a baud rate of 4Mbps?

Regards,

Luca