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

[Jakub Vaněk]

On 2/22/26 16:15, Andrew Lunn wrote:
> 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.

Thank you, that is encouraging. Handling the YT8821 PHY reset
and configuration in U-Boot should then indeed be sufficient.

Best regards,
Jakub