[PATCH] serial: 2.6.9rc1 pick nearest baud rate divider

[roger blofeld]

This patch modifies uart_get_divisor to select the nearest baud rate
divider rather than the lowest. It minimizes baud rate errors.

For example, if uartclk is 33000000 and baud is 115200 the ratio is
about 17.9
The current code selects 17 (5% error) but should select 18 (0.5%
error)

-roger

===== drivers/serial/serial_core.c 1.87 vs edited =====
--- 1.87/drivers/serial/serial_core.c   2004-06-29 09:43:58 -05:00
+++ edited/drivers/serial/serial_core.c 2004-09-15 14:04:34 -05:00
@@ -403,7 +403,7 @@
        if (baud == 38400 && (port->flags & UPF_SPD_MASK) ==
UPF_SPD_CUST)
                quot = port->custom_divisor;
        else
-               quot = port->uartclk / (16 * baud);
+               quot = (port->uartclk + (8 * baud)) / (16 * baud);
 
        return quot;
 }


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