[PATCH v9 07/10] arm64: dts: ls1046ardb: Add serdes bindings

[Sean Anderson]

On 1/27/23 11:15, Krzysztof Kozlowski wrote:
> On 27/01/2023 17:11, Sean Anderson wrote:
>>>>>>
>>>>>>  .../boot/dts/freescale/fsl-ls1046a-rdb.dts    | 112 ++++++++++++++++++
>>>>>>  drivers/phy/freescale/Kconfig                 |   1 +
>>>>>
>>>>> The phy driver Kconfig change shouldn't be part of this patch.
>>>>
>>>> I put it here for bisectability, since this is the point where we need
>>>> to enable it. But I can do this in a separate patch if you want.
>>>
>>> From DT ABI perspective, it's already broken anyway if you need to change
>>> kernel and DT atomically.
>> 
>> AIUI new kernels must work with old device trees, but new device trees need not
>> work with old kernels. So a change like this is fine, since the kernel won't
>> touch the serdes if it isn't supplied.
> 
> You used the argument "bisectability". If the patchset is not
> bisectable, the ABI is broken.

Well, because Shawn wants it in a separate patch I am just going to enable
the driver by default on Layerscape before adding the device nodes. That way we have

1. Base state, driver not enabled and node is disabled
2. Driver enabled but not used because the node is disabled
3. Driver enabled and bound to node

So there is never a case where the node is bound but the driver isn't enabled
(which would cause the ethernet drivers to fail to probe).

--Sean