Re: [PATCH net v1] net: phy: motorcomm: yt8821: disable MDIO broadcast address 0

[Andrew Lunn <andrew@lunn.ch>]

On Sun, Feb 22, 2026 at 10:52:28AM +0100, Jakub Vaněk wrote:
> On 2/22/26 09:28, Russell King (Oracle) wrote:
> > On Sun, Feb 22, 2026 at 05:22:55AM +0100, Jakub Vaněk wrote:
> >> I had hoped this would not happen on the Cudy router. The MediaTek
> >> Ethernet subsystem driver uses of_mdiobus_register(), so PHY address 0
> >> should not be probed unless it is explicitly described in the device
> >> tree. That said, I agree that with mdiobus_register() this would still
> >> be an issue.
> >>
> >> I was also hoping that moving the internal PHY would provide more
> >> flexibility in the device tree description of the YT8821. If the
> >> workaround were implemented in U-Boot by writing YT8821 MDIO registers
> >> at boot time, Linux would not be able to assert the YT8821 reset pin
> >> without losing that workaround.
> > 
> > Why would you want to assert the reset pin?
> > 
> 
> I don't currently have a solid reason to assert the reset pin.
> The two reasons I had in mind were mostly precautionary:

Being able to drive a PHY reset pin in Linux is relatively new. It was
added in 2016. Before that, we lived without this feature. If
anything, being able to reset the PHY causes more issues than it
solves.

So unless the PHY is actually broken and needs a reset to make it
work, it is probably better not to list the reset.

       Andrew