UART parent clock is by default the platform's xtal clock, which is
25 MHz.
The value defined in the driver, though, is 25.8048 MHz. This is a hack
for the suboptimal divisor calculation
Divisor = UART clock / (16 * baudrate)
which does not use rounding division, resulting in a suboptimal value
for divisor if the correct parent clock rate was used.
Change the code for divisor calculation to round to closest value, i.e.
Divisor = Round(UART clock / (16 * baudrate))
and change the parent clock rate value to that returned by
get_ref_clk().
This makes A3720 UART stable at standard UART baudrates between 1800 and
230400.
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
139d081384