[RFC 3/6] dt/bindings: Add bindings for Tegra20/30 NOR bus driver

[Mirza Krak]

2016-07-22 11:32 GMT+02:00 Jon Hunter <jonathanh at nvidia.com>:
>
> On 21/07/16 21:10, Mirza Krak wrote:
>> 2016-07-21 11:56 GMT+02:00 Jon Hunter <jonathanh at nvidia.com>:
>>>
>>> I wonder if it is worth mentioning that the chip-select specified in the
>>> "nvidia,config" prop should match that in the "ranges" prop unless you
>>> have some external decoding logic to provide an external chip-select.
>>> Which raises a question, what does the chip-select in the ranges
>>> actually represent? I am not sure if there is a common practice here for
>>> device tree when boards have external logic to provide additional
>>> chip-selects. I am sure this is quite common.
>>
>> I do not understand why CS pin setting in nvidia,config need to match
>> the "ranges" prop? Other then maybe cosmetics.
>
> Yes it would be cosmetic. That said, I even wonder if CS needs to be
> exposed at all given that they all map to the same CPU address space.
> Couldn't your binding for the CAN devices be as follows?
>
> nor at 70009000 {
>         ...
>
>         can at 48000000 {
>                 ...
>         };
>
>         can at 48040000 {
>                 ...
>         };
> };

This has also crossed my mind, maybe just get rid of the "ranges" prop
and do like you have above. But then again I do not know what is
preferred so I went with "ranges" prop initially.


>
> Problem is if you did have devices on different chip-selects then how
> would these be handled? They could not point to the same physical
> address. I am not sure if there is a way to do that in DT?

Having trouble following your though here. We do not have "different"
chip-selects?

Best Regards
Mirza