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Date: Fri, 15 Mar 2024 10:26:41 -0700
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Subject: Re: [PATCH 1/2] arm64: dts: mediatek: mt7622: set PHY address of
 MT7531 switch to 0x1f
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To: arinc.unal@arinc9.com, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Matthias Brugger
 <matthias.bgg@gmail.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: mithat.guner@xeront.com, erkin.bozoglu@xeront.com,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org
References: <20240314-for-mediatek-mt7531-phy-address-v1-0-52f58db01acd@arinc9.com>
 <20240314-for-mediatek-mt7531-phy-address-v1-1-52f58db01acd@arinc9.com>
From: Florian Fainelli <f.fainelli@gmail.com>
In-Reply-To: <20240314-for-mediatek-mt7531-phy-address-v1-1-52f58db01acd@arinc9.com>
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On 3/14/24 05:20, Arınç ÜNAL via B4 Relay wrote:
> From: Arınç ÜNAL <arinc.unal@arinc9.com>
> 
> The MT7531 switch listens on PHY address 0x1f on an MDIO bus. I've got two
> findings that support this. There's no bootstrapping option to change the
> PHY address of the switch. The Linux driver hardcodes 0x1f as the PHY
> address of the switch. So the reg property on the device tree is currently
> ignored by the Linux driver.
> 
> Therefore, describe the correct PHY address on boards that have this
> switch.

Can we call it a pseudo PHY to use a similar terminology as what is done 
through drivers/net/dsa/{bcm_sf2,b53}*?

This is not a real PHY as in it has no actual transceiver/digital signal 
processing logic, this is a piece of logic that snoops for MDIO 
transactions at that specific address and lets you access the switch's 
internal register as if it was a MDIO device.

LGTM otherwise!
-- 
Florian