Re: [PATCH 1/2] arm64: dts: mediatek: mt7622: set PHY address of MT7531 switch to 0x1f

[Florian Fainelli]

On 3/16/2024 12:43 AM, Arınç ÜNAL wrote:
> On 15.03.2024 20:26, Florian Fainelli wrote:
> > On 3/14/24 05:20, Arınç ÜNAL via B4 Relay wrote:
> > > From: Arınç ÜNAL <arinc.unal@xxxxxxxxxx>
> > >
> > > 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.
>
> I can get behind calling the switch a psuedo-PHY in the context of MDIO.
> However, as described on "22.2.4.5.5 PHYAD (PHY Address)" of "22.2.4.5
> Management frame structure" of the active standard IEEE Std 802.3™‐2022,
> the field is called "PHY Address". The patch log doesn't give an identifier
> as to what a switch is in the context of MDIO. Only that it listens on a
> certain PHY address which the term complies with IEEE Std 802.3™‐2022.
>
> So I don't see an improvement to be made on the patch log. Feel free to
> elaborate further.

I would just s/PHY/MDIO bus address/ since that is simply more generic, 
but if it is not written as-is in the spec, then I won't fight it much 
more than I already did.
--
Florian