[PATCH 1/2] arm64: dts: rockchip: fix Ethernet PHY not found on PX30 Cobra

[Quentin Schulz]

Hi Andrew,

On 2/2/26 2:52 PM, Andrew Lunn wrote:
> On Mon, Feb 02, 2026 at 11:27:25AM +0100, Quentin Schulz wrote:
>> From: Quentin Schulz <quentin.schulz at cherry.de>
>>
>> When not passing the PHY ID with an ethernet-phy-idX.Y compatible
>> property, the MDIO bus will attempt to auto-detect the PHY by reading
>> its registers and then probing the appropriate driver. For this to work,
>> the PHY needs to be in a working state.
>>
>> Unfortunately, the net subsystem doesn't control the PHY reset GPIO when
>> attempting to auto-detect the PHY. This means the PHY needs to be in a
>> working state when entering the Linux kernel. This historically has been
>> the case for this device, but only because the bootloader was taking
>> care of initializing the Ethernet controller even when not using it.
>> We're attempting to support the removal of the network stack in the
>> bootloader, which means the Linux kernel will be entered with the PHY
>> still in reset and now Ethernet doesn't work anymore.
>>
>> The devices in the field only ever had a TI DP83825, so let's simply
>> bypass the auto-detection mechanism entirely by passing the appropriate
>> PHY IDs via the compatible.
>>
>> Cc: stable at vger.kernel.org
>> Fixes: bb510ddc9d3e ("arm64: dts: rockchip: add px30-cobra base dtsi and board variants")
>> Signed-off-by: Quentin Schulz <quentin.schulz at cherry.de>
> 
> What is the justification for stable?
> 

Bootloader without network stack = no network in Linux.

Cheers,
Quentin