[U-Boot-Users] Breakage of board ports on new features.

Kumar Gala galak at kernel.crashing.org
Tue Dec 5 03:10:56 CET 2006

On Dec 4, 2006, at 7:13 PM, Tolunay Orkun wrote:

> Kumar Gala wrote:
>> On Dec 4, 2006, at 5:20 PM, Timur Tabi wrote:
>>> Wolfgang Denk wrote:
>>>> Are you absolutely sure we will *never* want to make a difference
>>>> between a MPC8349 and any other type of MPC834x?
>>>> What is the exact problem you're addressing?
>>> I think Kumar's point is that the code that's correctly marked  
>>> with  CONFIG_MPC8349 is not 8349-specific.  It's 834x-specific,  
>>> and there  already is a macro for 834x.  If someone were to add  
>>> support for an  8343 or 8347, they would need to apply Kumar's  
>>> patch anyway.
>>> *IF* some of this code is really 8349-specific, then the person   
>>> adding support for the 8343 or 8347 would need to modify this  
>>> code  again.  However, I don't think that's going to happen.
>> This is exactly what I'm saying.  The CONFIG_MPC8349 was too  
>> specific  and really meant CONFIG_MPC834X and thus I changed it.   
>> If/when  someone's got something that is MPC8349 specific they can  
>> re- introduce CONFIG_MPC8349.
> The AMCC 4XX based boards we define CONFIG_PPC4XX (for the family)  
> as well as CONFIG_PPC405GP (for example) for specific processor  
> support. The X'd version is used to enable common code while the  
> specific version is used whenever divergences exist from the common  
> code. Right now there might not be a specific difference from  
> MPC8349 code but it might be good to define both MPC8349 and  
> MPC834X for sake of consistency and for future proofing. Without  
> defining the specific version when it is time to introduce that  
> divergence you would wonder what boards were using the MPC8349 and  
> what not (unless the board name gives it away).

The concept is nice, but I think we should add it when its needed.   
The differences between the MPC834X family of processors are handled  
by features and not by specifying the specific processor.  This is  
because even on the specific processor you can choose to enable or  
disable the feature (PCI2, 32/64-bit ddr, etc.).

When someone comes up with a good reason for having a CONFIG_MPC8349  
then we should add it, until then I think its likely to get used  
incorrectly (as it already has been).

- k

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