Subject: Re: [PATCH 09/15] [POWERPC] 86xx: Add uli1575 pci-bridge sector to MPC8641HPCN dts file.

From: Segher Boessenkool <[email-masked]>
Date: Wed, 27 Jun 2007 22:57:07 +0200

>>>> -		ranges = <0 f8000000 00100000>;
>>>> -		reg = <f8000000 00100000>;	// CCSRBAR 1M
>>>> +		ranges = <00001000 f8001000 000ff000
>>> [...]
>>>> +		reg = <f8000000 00001000>;	// CCSRBAR
>>>
>>> This can't be right, and I suspect it will break any kernel access to
>>> the first 0x1000 bytes of the CCSR_BAR space.  reg should actually
>>> describe the register space of the SOC.  If ranges needs to specify
>>> that, too, they should be able to be redundant.  But this looks like
>>> a big hack, to me.  Am I missing something?
>>
>> "reg" and "ranges" can never overlap really.
>>
>> Is this the special case where the PHB is visible in
>> PCI configuration space?
>>
>> Or, please explain what CCSR_BAR is...
>
> Its a 1M MMIO register space on the SOC (all device registers on the 
> SOC live there).

Okay, so it has nothing to do with PCI configuration space?

There is "BAR" in the name, so it is a movable range?  Where
is the base address set?

What is the relationship between (in the example) the address
ranges x'f800_0000+1000 and x'f800_1000+ff000?

Segher