[U-Boot] CONFIG_BAUDRATE doesn't match

[Stefan Roese]

On 29.08.2013 18:08, txcotrader wrote:
> I'm working with an AMCC based board and I'm running into an issue when I
> set my uart0 baud rate. In the include/configs/amcc-common.h there is the
> following code:
> 
> #define CONFIG_BAUDRATE      115200
> #define CONFIG_SYS_BAUDRATE_TABLE  \
>     {300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400}
> 
> but after checking it on the o-scope it's not at 115200 baud. It seems like
> there is an offset of 3 because if I set the following bauds I get values on
> the o-scope like so:
> 
> #define CONFIG_BAUDRATE      9600  // o-scope baud = 57600
> #define CONFIG_BAUDRATE      19200  // o-scope baud = 115200
> #define CONFIG_BAUDRATE      38400  // o-scope baud = 230400
> 
> Could someone point me in the direction of how this may be happening?

Which 4xx variant is used? Do you have an external clock for the uarts?
Then you need to check if this value is configured correctly:

#define CONFIG_SYS_EXT_SERIAL_CLOCK     11059200

If your baudrate is generated from the internal clocks then you need to
make sure that this values are set:

#define CONFIG_SYS_NS16550_CLK          get_serial_clock()
#undef CONFIG_SYS_EXT_SERIAL_CLOCK

Which did you configure? And for which CPU vaiant?

Thanks,
Stefan