[PATCH] Fix the LPC47M192 SuperIO on the MPC8641 HPCN

[Andy Fleming]

On Jun 7, 2007, at 11:35, Segher Boessenkool wrote:

>>> Hardcoded I/O port numbers always worry me a little. I know that  
>>> this
>>> is
>>> supposed to work in general, but can't you read the I/O port range
>>> from
>>> a device tree property?
>>
>> I suppose I could create a device node for the Super I/O config
>> registers and use those instead of hardcoding it here.
>
> I'd just hide it all, do this setup in the firmware,
> where it belongs, and don't expose the superio config
> in the device tree.


No more.  No more firmware-only initializations.  It sounds great, in  
principle, until you actually have to figure out why someone's setup  
isn't working.  I'm tired of having to see if the dts, u-boot, and  
Linux are in sync.  If Linux wants to use a device, I think it's not  
unreasonable to have it setup the device itself.  That way, Linux can  
do whatever it wants with the device, and not have to rely on U-Boot  
(or some other firmware) setting up the appropriate bits.


>
>> superio_cfg at 4e {
>> 	reg = <1 4e 2>;
>> 	compatible = "smsc-lpc47m192-cfg";
>> };
>>
>> I'm not sure if the name and compatible properties are appropriate
>> though.  Any recommendations?
>
> "superio" and "smsc,lpc47m192" I'd say.  You also
> then should link the logical devices on the superio
> to the device nodes that represent those.  I'm not
> sure this is all worth it, this is low-level setup
> the firmware should do and everything else can treat
> it as a black box.


Please...no.  What happens next is that we find a small bug that  
requires we modify U-Boot to do the initialization slightly  
differently, and then requires Linux to act slightly differently.   
And then I get emails every day from people wondering why their  
boards don't work.

Andy