[RFC PATCH 2/2] ARM: DT: kernel: DT cpu node bindings update

[swarren@wwwdotorg.org (Stephen Warren)]

On 04/17/2013 10:02 AM, Nicolas Pitre wrote:
> On Wed, 17 Apr 2013, Stephen Warren wrote:
> 
>> On 04/17/2013 03:14 AM, Mark Rutland wrote:
>>> Hi Stephen,
>>>
>>>>> +	- enable-method
>>>>> +		Usage: required on ARM 64-bit systems, optional on ARM 32-bit
>>>>> +		       systems
>>>>> +		Value type: <string>
>>>>> +		Definition: On ARM 64-bit systems must be "spin-table" [1].
>>>>
>>>> Can that be an integer instead? with dtc+cpp support, that shouldn't
>>>> hurt the eyes too much any more.
>>>
>>> The "enable-method" property is described as a stringlist by ePAPR, and is
>>> currently in use on arm64 as such. It *must* remain a string(list) for arm64.
>>>
>>> Having it as an integer for arm is only going to cause us additional work,
>>> makes it impossible to share a common dt between 64bit and 32bit, and goes
>>> against the standard. I think it should be a stringlist for arm.
>>
>> OK, that's a great reason for this case.
>>
>> I hope we don't introduce any more standards that use strings, but that
>> may just be my personal preference...
> 
> I think in any standard, strings are far easier to deal with.  
> Especially with config stuff which is far from being performance 
> critical. Strings are much less prone to conflicts.  It is too easy to 
> "extend" a standard by assigning meanings to free numerical values just 
> to discover that someone else did use the same numbers for other 
> meanings.
> 
> In order to avoid this issue, a central authority has to be established 
> to assign numbers out while strings are fine without that most of the 
> time.

For DT, all strings or numbers must always be documented in the DT
binding, so there's no risk of conflict there.