Hi Scott,

On Thursday 20 November 2008, Scott Wood wrote:

On Thu, Nov 20, 2008 at 01:32:23PM +0100, Laurent Pinchart wrote:

quoted

Instead of rounding the divider down, improve the baud-rate generators
accuracy by rounding to the nearest integer.

Signed-off-by: Laurent Pinchart <redacted>

This makes things worse on mpc8272ads -- the result of the division is
13.56, but I only get error-free serial output when rounding down.  I
don't think the remote end has timing problems, as I don't see this with
any other board.

I get exactly the opposite here with an mpc8248 base board. Rounding down 
makes 115200bds completely unreliable :-/

Could you measure the serial baudrate with and without the patch using an 
oscilloscope ?

Possibly the crystal is a little off,

That's always possible.

or maybe it's just better to be a little too fast than a little too slow for
some reason? 

Maybe we should change CPM_CLK to be MAIN_CLK/4 rather than MAIN_CLK/16
when the BRG clock is below a certain frequency.

Isn't that the job of the boot loader ? Accuracy would be improved, but power 
consumption will raise as well :-/

Best regards,

Laurent Pinchart