Re: [PATCH 2/2] dt-bindings: net: dsa: mediatek,mt7530: document MDIO-bus

Arınç ÜNAL
2023-04-30T12:53:23Z

On 30.04.2023 15:44, Daniel Golle wrote:
> On Sun, Apr 30, 2023 at 03:34:43PM +0300, Arınç ÜNAL wrote:
>> On 30.04.2023 14:28, David Bauer wrote:
>>> Document the ability to add nodes for the MDIO bus connecting the
>>> switch-internal PHYs.
>>
>> This is quite interesting. Currently the PHY muxing feature for the MT7530
>> switch looks for some fake ethernet-phy definitions on the mdio-bus where
>> the switch is also defined.
>>
>> Looking at the binding here, there will be an mdio node under the switch
>> node. This could be useful to define the ethernet-phys for PHY muxing here
>> instead, so we don't waste the register addresses on the parent mdio-bus for
>> fake things. It looks like this should work right out of the box. I will do
>> some tests.
>>
>> Are there any examples as to what to configure on the switch PHYs with this
>> change?
>>
>>>
>>> Signed-off-by: David Bauer <mail@david-bauer.net>
>>> ---
>>> .../devicetree/bindings/net/dsa/mediatek,mt7530.yaml | 6 ++++++
>>> 1 file changed, 6 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
>>> index e532c6b795f4..50f8f83cc440 100644
>>> --- a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
>>> +++ b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
>>> @@ -128,6 +128,12 @@ properties:
>>> See Documentation/devicetree/bindings/regulator/mt6323-regulator.txt for
>>> details for the regulator setup on these boards.
>>> + mdio:
>>> + $ref: /schemas/net/mdio.yaml#
>>> + unevaluatedProperties: false
>>> + description:
>>> + Node for the internal MDIO bus connected to the embedded ethernet-PHYs.
>>
>> Please set this property as false for mediatek,mt7988-switch as it doesn't
>> use MDIO.
>
> Well, quite the opposite is true. This change is **needed** on MT7988 as
> the built-in 1GE PHYs of the MT7988 are connected to the (internal) MDIO
> bus of the switch. And they do need calibration data assigned as nvmem
> via device tree.
>
> tl;dr: Despite not being connected via MDIO itself also MT7988 exposes an
> internal MDIO bus for the switch PHYs.

Got it, thanks.

Arınç