Re: [PATCH] net: usb: lan78xx: scan all MDIO addresses on LAN7801

[Andrew Lunn]

On Sat, Feb 14, 2026 at 12:15:21PM +0000, Martin Pålsson wrote:
> The LAN7801 is designed exclusively for external PHYs (unlike the
> LAN7800/LAN7850 which have internal PHYs), but lan78xx_mdio_init()
> restricts PHY scanning to MDIO addresses 0-7 by setting phy_mask to
> ~(0xFF). This prevents discovery of external PHYs wired to addresses
> outside that range.
> 
> One such case is the DP83TC814 100BASE-T1 PHY, which is typically
> configured at MDIO address 10 via PHYAD bootstrap pins and goes
> undetected with the current mask.
> 
> Set phy_mask to 0 for the LAN7801 so that all 32 MDIO addresses are
> scanned during bus registration, allowing any external PHY to be
> discovered regardless of its address.
> 
> Signed-off-by: Martin Pålsson <martin@xxxxxxxxxxxx>

Since you are submitting this for net, it should have a Fixes: tag.

Also, since this is a 100Base PHY, i assume dev->interface needs to be
PHY_INTERFACE_MODE_MII? But it looks like lan78xx_get_phy() is hard
coding it to PHY_INTERFACE_MODE_RGMII_ID for the 7801. How is this
working out for you?

	Andrew