[PATCH v2 03/11] dt-bindings: arm: mediatek: add 'mediatek,pn_swap' property

[Krzysztof Kozlowski]

On 08/02/2023 14:51, Daniel Golle wrote:
> On Wed, Feb 08, 2023 at 10:32:53AM +0100, Krzysztof Kozlowski wrote:
>> On 07/02/2023 19:00, Daniel Golle wrote:
>>> ...
>>>> 3. Does not look like property of this node. This is a clock controller
>>>> or system controller, not SGMII/phy etc.
>>>
>>> The register range referred to by this node *does* represent also an
>>> SGMII phy. These sgmiisys nodes also carry the 'syscon' compatible, and
>>> are referenced in the node of the Ethernet core, and then used by
>>> drivers/net/ethernet/mediatek/mtk_sgmii.c using syscon_node_to_regmap.
>>> (This is the current situation already, and not related to the patchset
>>> now adding only a new property to support hardware which needs that)
>>
>> Just because a register is located in syscon block, does not mean that
>> SGMII configuration is a property of this device.
> 
> It's not just one register, the whole SGMII PCS is located in those
> mediatek,sgmiisys syscon nodes.

Then maybe this should be a PCS PHY device instead of adding properties
unrelated to clock/system controller? I don't know, currently this
binding says it is a provider of clocks...

> 
>>
>>>
>>> So: Should I introduce a new binding for the same compatible strings
>>> related to the SGMII PHY features? Or is it fine in this case to add
>>> this property to the existing binding?
>>
>> The user of syscon should configure it. I don't think you need new
>> binding. You just have to update the user of this syscon.
> 
> Excuse my confusion, but it's still not entirely clear to me.
> So in this case I should add the description of the added propterty of
> the individual SGMII units (there can be more than one) to
> Documentation/devicetree/bindings/net/mediatek,net.yaml
> eventhough the properties are in the sgmiisys syscon nodes?

I guess the property should be in the node representing the SGMII. You
add it now to the clock (or system) controller, so it does not look
right. It's not a property of a clock controller.

Now which node should have this property depends on your devices - which
I have no clue about, I read what is in the bindings.

> 
> If so I will have to figure out how to describe properties of other
> nodes in the binding of the node referencing them. Are there any
> good examples for that?

phys and pcs'es?

> 
> Or should the property itself be moved into yet another array of
> booleans which should be added in the node describing the ethernet
> controller and referencing these sgmiisys syscons using phandles?

Best regards,
Krzysztof