[U-Boot-Users] cpu/mpc85xx/fdt.c forcing incorrect UART clock into fdt.

[Jerry Van Baren]

Paul Gortmaker wrote:
> I was updating a sbc8560 from u-boot v1.2.0 to git-current, and found
> that I'd loose the kernel serial console when the 8250 driver took over
> from udbg0 when using u-boot 1.3.x  (booting via tftp'ing the dtb and
> the uImage separately)
> 
> I eventually tracked it down to mpc85xx/fdt.c stomping on the contents
> of the UART clockrate in the dtb.  Since the sbc8560 is sort of
> different -- in that it has external UARTs (instead of SOC/CPM), I'm
> guessing few other boards see this problem, because bi_busfreq is
> really their correct UART clk.
> 
> I fixed it with this simple patch, but I was wondering whether it would
> be better to alternatively just check if the dtb value is zero, and 

Not defined: I would have serious heartburn if the .dts/dtb value were 
defined to be zero.  Define or define not, there should be no zero (with 
apologies to Yoda).

> then only insert a value; otherwise leave it alone...
> 
> Paul.

Changing the fixup last parameter (create) from "1" to "0" will prevent 
overriding an existing value.  Note that this will *not* override a 
silly value (e.g. 0), so, if you do this, the dtb must either not have 
the clock-frequency defined or have a correct value in that property. 
This would have the good effect of allowing the board specific clock to 
be defined in the dtb where it belongs, but still support the older 
style approach of compiling it in.

This seems like a good improvement (your patch, but changing the "1" to 
"0") to me, but I'm not a 85xx expert.

> diff --git a/cpu/mpc85xx/fdt.c b/cpu/mpc85xx/fdt.c
> index 92952e6..bd43073 100644
> --- a/cpu/mpc85xx/fdt.c
> +++ b/cpu/mpc85xx/fdt.c
> @@ -224,7 +224,7 @@ void ft_cpu_setup(void *blob, bd_t *bd)
>  
>  #ifdef CFG_NS16550
>  	do_fixup_by_compat_u32(blob, "ns16550",
> -		"clock-frequency", bd->bi_busfreq, 1);
> +		"clock-frequency", CFG_NS16550_CLK, 1);
>  #endif
>  
>  #ifdef CONFIG_CPM2

Best regards,
gvb