Re: [PATCH net-next 0/3] net: mdio: Clause 45 support for

[Kordian Chmielewski <kudzo51@gmail.com>]

On Fri, 13 Nov 2026 13:15:51 -0800, Florian Fainelli wrote:
> This patch series adds support for Clause 45 MDIO operations within the
> mdio-bcm-unimac driver.

Tested on a TP-Link Archer AX6000 (BCM4908) with OpenWrt and Linux
6.18.55, with this series in place of our own C45 support. The bus has
the switch's internal PHYs, which are C22, and the BCM54991E WAN PHY at
address 0x1d, which is C45.

The BCM54991E takes its firmware over C45 and links at 1000 Mbit/s,
ethtool -r brings the link back, and the WAN carries traffic. 8000
reads through SIOCGMIIREG gave no errors. Such a read, ioctl included,
takes 18 us on average for C45 and 10 us for C22, against 64 and 32 us
with the old polling, which starts with a fixed 30 us delay per frame
(our C45 code used the same wait).

The PHY's DT node has only its ID compatible; our PHY driver, which is
not upstream, switches it to C45 in probe. So the new check in
unimac_mdio_reset() never matched, and since the bus is registered
from DT, the C45 scan at registration did not run either.

Tested-by: Kordian Chmielewski <kudzo51@gmail.com>