[U-Boot] [PATCH 4/5] powerpc: keymile: Add a check for the PIGGY debug board

[Ben Warren]

Hi Gary,

Gary Jennejohn wrote:
> On Thu, 13 Nov 2008 09:30:51 -0800
> Ben Warren <biggerbadderben at gmail.com> wrote:
>
>   
>> Heiko Schocher wrote:
>>     
>>> Hello Ben
>>>
>>> Ben Warren wrote:
>>>   
>>>       
>>>> Heiko Schocher wrote:
>>>>   
>>>>     
>>>>         
>>>>> Check the presence of the PIGGY on the keymile boards mgcoge,
>>>>> mgsuvd and kmeter1. If the PIGGY is not present, dont register
>>>>> this Ethernet device.
>>>>>
>>>>> Signed-off-by: Heiko Schocher <hs at denx.de>
>>>>> ---
>>>>>     
>>>>>       
>>>>>           
>>>> This looks like useful stuff to have, but I'd prefer that you put the 
>>>> check logic in board_eth_init() rather than adding to the individual 
>>>> device drivers.  I know the 8260 SCC driver is the older style, which 
>>>> precludes the use of board_eth_init, but I'll convert it if you're able 
>>>> to test.
>>>>   
>>>>         
>
> Unfortunately, this approach won't work.  First of all, the 82xx SCC
> driver is now initialized in cpu_eth_init(), which knows nothing about
> board-specific peculiarities like the PIGGY.  Secondly, the HDLC
> driver for Keymile has to be initialized in board_eth_init(), and it
> has nothing to do with the PIGGY.  Putting the check in board_eth_init()
> would break it completely.  I looked at Heiko's latest patch and couldn't
> figure out a way to cleanly differentiate between initializing the HDLC
> driver and checking whether the PIGGY was present fo the other ENET drivers.
>
>   
I think you're missing something.  You can put whatever logic you want 
in board_eth_init(), *including* calling cpu_eth_init().  As long as  
board_eth_init() returns >= 0, cpu_eth_init() will never get called by 
eth_initialize().  When I designed this, my intention (although not well 
communicated) was that board_eth_init() would always return >= 0, and 
that the -1 return code would only be used by the weak function in 
net/eth.c  There's pretty serious flexibility here and I urge you to 
look again.

regards,
Ben