Subject: Re: [PATCH] [POWERPC] 85xx: Add basic Uniprocessor MPC8572 DS port

From: Olof Johansson <[email-masked]>
Date: Tue, 11 Sep 2007 10:55:58 -0500

On Tue, Sep 11, 2007 at 10:50:18AM -0500, Kumar Gala wrote:
>>> diff --git a/arch/powerpc/platforms/85xx/mpc85xx_ds.c 
>>> b/arch/powerpc/platforms/85xx/mpc85xx_ds.c
>>> index 3a5c3c4..1e2eba8 100644
>>> --- a/arch/powerpc/platforms/85xx/mpc85xx_ds.c
>>> +++ b/arch/powerpc/platforms/85xx/mpc85xx_ds.c
>>> @@ -181,6 +181,23 @@ static int __init mpc8544_ds_probe(void)
>>>  	}
>>>  }
>>>
>>> +/*
>>> + * Called very early, device-tree isn't unflattened
>>> + */
>>> +static int __init mpc8572_ds_probe(void)
>>> +{
>>> +	unsigned long root = of_get_flat_dt_root();
>>> +
>>> +	if (of_flat_dt_is_compatible(root, "MPC8572DS")) {
>>> +#ifdef CONFIG_PCI
>>> +		primary_phb_addr = 0x8000;
>>> +#endif
>>> +		return 1;
>>> +	} else {
>>> +		return 0;
>>> +	}
>>> +}
>>> +
>>>  define_machine(mpc8544_ds) {
>>>  	.name			= "MPC8544 DS",
>>>  	.probe			= mpc8544_ds_probe,
>>> @@ -194,3 +211,17 @@ define_machine(mpc8544_ds) {
>>>  	.calibrate_decr		= generic_calibrate_decr,
>>>  	.progress		= udbg_progress,
>>>  };
>>> +
>>> +define_machine(mpc8572_ds) {
>>> +	.name			= "MPC8572 DS",
>>> +	.probe			= mpc8572_ds_probe,
>>> +	.setup_arch		= mpc85xx_ds_setup_arch,
>>> +	.init_IRQ		= mpc85xx_ds_pic_init,
>>> +#ifdef CONFIG_PCI
>>> +	.pcibios_fixup_bus	= fsl_pcibios_fixup_bus,
>>> +#endif
>>> +	.get_irq		= mpic_get_irq,
>>> +	.restart		= mpc85xx_restart,
>>> +	.calibrate_decr		= generic_calibrate_decr,
>>> +	.progress		= udbg_progress,
>>> +};
>>
>> How different are these boards really? Could you just detect MPC85xxDS
>> and have a generic platform for them, or are they different enough that
>> you need individual ones for it?
>
> I wanted a different probe.  I figured having a different struct was a 
> simple solution.

Seems like the only reason to need that is the setting of
primary_phb_addr.  Can't that information be derived out of the device
tree instead? That'd avoid alot of code duplication (code that includes
ifdefs, FWIW :-)

It just seems like a slippery slope. I'm not objecting directly to this
patch, but I think it should be fixed for the longer term.

-Olof