Re: [PATCH net-next v2] net: phy: bcm84881: add BCM84891/BCM84892 support

On 24.3.2026 20:06, Daniel Wagner wrote:

The BCM84891 and BCM84892 are 10GBASE-T PHYs in the same family as the
BCM84881, sharing the register map and most callbacks. They add USXGMII
as a host interface mode.

bcm8489x_config_init() is separate from bcm84881_config_init(): it
allows only USXGMII (the only host mode available on the tested
hardware) and clears MDIO_CTRL1_LPOWER, which is set at boot on the
tested platform. Does not recur on ifdown/ifup, cable events, or
link-partner advertisement changes, so config_init is sufficient.

For USXGMII, read_status() skips the 0x4011 host-mode register: it
returns the same value regardless of negotiated copper speed (USXGMII
symbol replication). Speed comes from phy_resolve_aneg_linkmode() via
standard C45 AN resolution.

Tested on TRENDnet TEG-S750 (RTL9303 + 1x BCM84891 + 4x BCM84892)
running OpenWrt, where the MDIO controller driver is currently
OpenWrt-specific. Link verified at 100M, 1G, 2.5G, 10G.

Signed-off-by: Daniel Wagner <redacted>
---
Changes in v2:
- Separate bcm8489x_config_init() that allows only USXGMII. v1 also
  allowed USXGMII for BCM84881 (which doesn't support it), and put
  SGMII/2500BASEX/10GBASER in the 8489x possible_interfaces which I
  can't substantiate on this hardware. (Russell)
- LPOWER clear moved from config_aneg to config_init. Characterized on
  hardware: boot-time only, does not recur on ifdown/ifup, cable
  events, or link-partner advertisement changes. (Russell)
- Dropped LED support; will figure out the PHY LED framework approach
  for bicolor speed-mapped LEDs as a follow-up. (Russell, Andrew)
- PHY_ID_MATCH_MODEL(). (Russell, Andrew)
- is_bcm8489x() helper removed; the interface mode now suffices as a
  discriminator in read_status since only the 8489x config_init allows
  USXGMII.

v1: 
https://lore.kernel.org/netdev/20260324152503.1522071-2-wagner.daniel.t@gmail.com/ (local)

[...]

Checked the patch against the public datasheet and everything resolves.

Reviewed-by: Nicolai Buchwitz <redacted>