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

[Andrew Lunn]

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?

     Andrew