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

From: "Arınç ÜNAL" <arinc.unal@arinc9.com>
To: Daniel Golle <daniel@makrotopia.org>
Cc: David Bauer <mail@david-bauer.net>, Andrew Lunn <andrew@lunn.ch>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Vladimir Oltean <olteanv@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	AngeloGioacchino Del Regno
	<angelogioacchino.delregno@collabora.com>,
	Landen Chao <Landen.Chao@mediatek.com>,
	DENG Qingfang <dqfext@gmail.com>,
	Sean Wang <sean.wang@mediatek.com>,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH 2/2] dt-bindings: net: dsa: mediatek,mt7530: document MDIO-bus
Date: Sun, 30 Apr 2023 15:52:31 +0300	[thread overview]
Message-ID: <4270c379-ae34-0002-e812-874180257d9e@arinc9.com> (raw)
In-Reply-To: <ZE5inBwZrOE-9uyA@makrotopia.org>

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

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