Re: [PATCH] [POWERPC] Add docs for Freescale PowerQUICC SATA device tree nodes

[Kumar Gala <galak@kernel.crashing.org>]

On Jan 22, 2008, at 3:54 PM, Grant Likely wrote:

> On 1/22/08, Kumar Gala <galak@kernel.crashing.org> wrote:
>> Signed-off-by: Li Yang <leoli@freescale.com>
>> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
>> ---
>> Documentation/powerpc/booting-without-of.txt |   30 ++++++++++++++++ 
>> ++++++++++
>> 1 files changed, 30 insertions(+), 0 deletions(-)
>>
>> diff --git a/Documentation/powerpc/booting-without-of.txt b/ 
>> Documentation/powerpc/booting-without-of.txt
>> index 3584c33..387310a 100644
>> --- a/Documentation/powerpc/booting-without-of.txt
>> +++ b/Documentation/powerpc/booting-without-of.txt
>> @@ -2743,6 +2743,36 @@ platforms are moved over to use the  
>> flattened-device-tree model.
>>                };
>>        };
>>
>> +    * Freescale 8xxx/3.0 Gb/s SATA nodes
>> +
>> +    SATA nodes are defined to describe on-chip Serial ATA  
>> controllers.
>> +    Each SATA port should have its own node.
>> +
>> +    Required properties:
>> +    - compatible        : compatible list, contains 2 entries,  
>> first is
>> +                        "fsl,CHIP-sata", where CHIP is the processor
>> +                        (mpc8315, mpc8379, etc.) and the second is
>> +                        "fsl,pq-sata"
>
> As discussed on IRC, I don't like the approach of trying to define
> generic names for these ip cores.  Too much can change in the future
> to make the definition of the generic type drift over time.  Better to
> always refer to exact chip variants.
>
> ie.  Assuming mpc8315 was the first part to contain the sata core; the
> dts should claim "fsl,CHIP-sata","fsl,mpc8315-sata" instead of
> "fsl,CHIP-sata","fsl,pq-sata".
>
> It ends up being the same amount of work to support, but it doesn't
> fall into the trap of making stuff up.
>
> Another example; when describing serial ports, we still use an
> *ancient* device to claim compatibility with: "ns16550".  ns16550 is
> specific, not generic, yet everyone still knows what it means.

Think of the 'specific' name as 'fsl,pq-sata'.  Just like ns16550  
there are lot of variants that do slightly different things which is  
captured by the even more specific 'fsl,mpc8313-sata' name.

I note your disagreement. :)

- k