net: ethernet: mtk_eth_soc: populate lpi_interfaces to fix EEE support

phylink_create() decides once and for all that a MAC supports managed
EEE, and it requires the tx_lpi ops plus non-empty lpi_capabilities and
lpi_interfaces. mtk_add_mac() leaves lpi_interfaces empty.

So ever since EEE support was added, ethtool has answered "Not
supported" on every MAC that uses mtk_phylink_ops, and
phy_disable_eee() has locked userspace out of turning EEE on. MT7628
is unaffected, as rt5350_phylink_ops has no tx_lpi methods.

Leave 2.5 Gbps out of both bitmaps, and the xGMII modes that
mtk_mac_enable_tx_lpi() already refuses. MAC_MCR folds SPEED_2500 onto
MAC_MCR_SPEED_1000, so MAC_MCR_EEE1G would govern LPI on such a link,
and that is unvalidated rather than known unsupported: MediaTek's SDK
driver sets the EEE force bits for 100 Mbps and 1 Gbps only, and the
unit of the wakeup timers is undocumented with the port clock at
2.5 times the rate.

mtk_mac_enable_tx_lpi() programs wake-up times taken from MT7531's
reset values, and the SoC's own field has no reset value to fall
back on. Only MT7981 has been seen to exit LPI cleanly with them, so
the LPI interfaces sit behind a new MTK_GMAC_EEE capability that only
MT7981 sets; every other SoC keeps the current behaviour until it has
been confirmed.

LPI stays off until userspace enables it, but the EEE advertisement of
a PHY that advertises it out of reset comes back, since phylink stops
force-clearing it.

Fixes: 952d7325362f ("net: ethernet: mediatek: add EEE support")
Signed-off-by: Aleksei Sviridkin <f@lex.la>
Link: https://patch.msgid.link/20260903123644.23800-3-f@lex.la
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions