[PATCH net v3 0/2] net: restore EEE on MediaTek switches and SoC MACs

[PATCH net v3 0/2] net: restore EEE on MediaTek switches and SoC MACs

[Aleksei Sviridkin]

Both drivers fill in phylink_config.lpi_capabilities and
lpi_timer_default but never lpi_interfaces. phylink treats a MAC as
supporting managed EEE only when the tx_lpi methods are implemented and
BOTH bitmaps are non-empty, which phylink_create() decides once and for
all, so EEE has been off on every mt753x port and on every mtk_eth_soc
MAC that uses mtk_phylink_ops since the two conversions named in the
Fixes: tags. Because the tx_lpi methods ARE implemented, phylink takes
the other branch and calls phy_disable_eee(), which fills
eee_disabled_modes - so userspace cannot enable EEE either.

On an MT7981B board with an MT7531 switch, before these patches:

  == lan1
  Cannot get EEE settings: Not supported
  == lan2
  Cannot get EEE settings: Not supported
  == lan3
  Cannot get EEE settings: Not supported
  == lan4
  Cannot get EEE settings: Not supported
  == wan
  Cannot get EEE settings: Not supported

lan1-3 are the MT7531 internal PHYs, lan4 is an EN8811H on switch port
5 whose MAC side runs 2500BASE-X rate matched to a 1 Gbps media link,
and wan is the mtk_eth_soc MAC with its directly attached 1 Gbps PHY -
so both drivers are covered.

Each patch fills lpi_interfaces from supported_interfaces and leaves
2.5 Gbps out of both bitmaps for now. LPI above 1 Gbps is unvalidated
rather than unsupported: both MACs fold 2.5 Gbps onto their 1 Gbps
speed encoding, so the 1 Gbps EEE force bit is what would govern it.
MediaTek's SDK driver sets the force bits for 100 Mbps and 1 Gbps only,
EEE signalling on 2500BASE-X is outside 802.3, and the 1 us unit of the
wakeup timers is undocumented at 2.5 times the port clock.

Neither driver sets eee_enabled_default, so LPI stays off until
userspace asks for it with ethtool --set-eee. The EEE advertisement is
a different matter: phylink stops force-clearing it, so a PHY that
advertises EEE out of reset advertises it again and the link may
negotiate EEE, without this MAC asserting LPI. MT7531's internal PHYs
and EN7528 are the exceptions, for the reasons in patch 1. Devicetree
eee-broken-* marks act at the PHY level and keep working, so a board
that already distrusts its PHYs stays protected: OpenWrt marks all
modes broken on MT7621's internal PHYs.

The two patches are independent and touch different subsystems; they
are sent together because they are the same bug.

Targeted at net as a regression fix with an active userspace lockout;
can be retargeted at net-next if maintainers prefer.

Based on net-next at 91ec20351349. Both driver files are byte
identical in net/main and the series applies there unchanged.

After the series, all five ports report:

  EEE status: disabled
  Tx LPI: disabled
  Supported EEE link modes:  100baseT/Full
                             1000baseT/Full
  Advertised EEE link modes:  Not reported

No 2.5G mode is offered, which is the narrowed lpi_capabilities, and
nothing is advertised until userspace asks. On this board no PHY came
out of reset advertising EEE, so the case where the advertisement
returns once phylink stops clearing it is not exercised here.

Enabling it on lan1, whose partner advertises EEE at both speeds:

  # ethtool --set-eee lan1 eee on
  EEE status: enabled - active
  Advertised EEE link modes:  100baseT/Full 1000baseT/Full
  Link partner advertised EEE link modes:  100baseT/Full 1000baseT/Full

  # ethtool --set-eee lan1 eee on tx-lpi on
  EEE status: enabled - active
  Tx LPI: 30 (us)

With LPI armed, 30 parallel ICMPv6 streams of 1400-byte payload, 300
packets each one second apart - so every gap crosses the LPI threshold
and the link enters and leaves LPI thousands of times over 300 s - lost
nothing: 300/300 on every stream, tx and rx error counters unchanged,
carrier_changes unchanged, and no mac_enable_tx_lpi errors in dmesg.

On wan the link partner advertises no EEE, so enabling it settles at
"enabled - inactive", which is the correct outcome, and the link
survived the autonegotiation restart. Its Tx LPI reads 1000 (us)
against lan1's 30; see the note below the scissors of patch 1.

lan4 keeps EEE disabled and never arms LPI, which is what dropping
2500BASE-X from lpi_interfaces is for. Forwarding through it was
lossless with no carrier change.

---
v3: both commit messages cut down to the Why, with the mechanism left
    to the diff and the detail below the scissors (Andrew Lunn); no
    code changes.
    https://lore.kernel.org/netdev/20260824024117.46154-1-f@lex.la/
v2: commit messages rewritten to carry the Why only, mechanism notes
    moved below the scissors (Andrew Lunn); comments and commit
    messages reworded so the 2.5 Gbps exclusion reads as unvalidated
    rather than impossible (Daniel Golle); no functional changes.
    https://lore.kernel.org/netdev/20260822195252.2934-1-f@lex.la/

Aleksei Sviridkin (2):
  net: dsa: mt7530: populate lpi_interfaces to fix EEE support
  net: ethernet: mtk_eth_soc: populate lpi_interfaces to fix EEE support

 drivers/net/dsa/mt7530.c                    | 24 ++++++++++++++++-----
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 22 ++++++++++++++++---
 2 files changed, 38 insertions(+), 8 deletions(-)

-- 
2.55.0

[PATCH net v3 1/2] net: dsa: mt7530: populate lpi_interfaces to fix EEE support

[Aleksei Sviridkin]

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. mt753x_phylink_get_caps() leaves lpi_interfaces empty.

So ever since the conversion to phylink managed EEE, ethtool has
answered "Not supported" on every mt753x port, and phy_disable_eee()
has locked userspace out of turning EEE on. That undoes what
commit 06dfcd4098cf ("net: dsa: mt7530: fix enabling EEE on MT7531
switch on all boards") arranged: EEE off by default, but reachable
with ethtool.

Leave the speeds above 1 Gbps out of both bitmaps. PMCR folds
SPEED_2500 and SPEED_10000 onto PMCR_FORCE_SPEED_1000, so
PMCR_FORCE_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.

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: 9cf21773f535 ("net: dsa: mt7530: convert to phylink managed EEE")
Signed-off-by: Aleksei Sviridkin <f@lex.la>
---

Ports that support neither 100 Mbps nor 1 Gbps are skipped because on
MT7988, EN7581 and AN7583 port 6 is 10 Gbps only and shares
PHY_INTERFACE_MODE_INTERNAL with the user ports, so the interface mask
alone cannot tell them apart. MT7531's internal PHYs keep the
advertisement mt7531_setup() zeroed and EN7528 keeps both bitmaps
empty, so EEE stays fully off there.

Two pre-existing things this patch makes live, neither addressed here:

- The unit of LPI_THRESH is still unspecified, as the comment above
  lpi_timer_default says. ethtool now reports 30 for a switch port
  against 1000 for the SoC MAC, which is a driver constant already in
  microseconds, and mtk_eth_soc treats a structurally identical field
  as milliseconds. Does anyone have the datasheet answer?

- mt753x_phylink_mac_enable_tx_lpi() sets the PMCR force-EEE bits
  without checking the resolved speed or interface, relying entirely on
  phylink never calling it above 1 Gbps. A check there would make the
  driver robust independently of lpi_interfaces being right.

v2, with the full argument for leaving the higher speeds out:
https://lore.kernel.org/netdev/20260824024117.46154-2-f@lex.la/
 drivers/net/dsa/mt7530.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 2b7be091c056..4ed6218df64b 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -3172,23 +3172,37 @@ static void mt753x_phylink_get_caps(struct dsa_switch *ds, int port,
 
 	config->mac_capabilities = MAC_ASYM_PAUSE | MAC_SYM_PAUSE;
 
+	priv->info->mac_port_get_caps(ds, port, config);
+
 	/* The EN7528 GPHYs report EEE capability, but negotiating EEE with
 	 * common link partners (e.g. Realtek GbE NICs) results in an unstable
 	 * link with dropped frames. Leave the LPI capabilities empty so that
 	 * phylink disables EEE on these PHYs and refuses to enable it from
-	 * userspace.
+	 * userspace. Ports that run at neither 100 Mbps nor 1 Gbps are left
+	 * empty too, since LPI above 1 Gbps is unvalidated.
 	 */
-	if (priv->id != ID_EN7528) {
+	if (priv->id != ID_EN7528 &&
+	    config->mac_capabilities & (MAC_100FD | MAC_1000FD)) {
 		u32 eeecr = mt7530_read(priv, MT753X_PMEEECR_P(port));
 
-		config->lpi_capabilities = MAC_100FD | MAC_1000FD | MAC_2500FD;
+		/* PMCR folds SPEED_2500 and SPEED_10000 onto
+		 * PMCR_FORCE_SPEED_1000, so LPI above 1 Gbps would be
+		 * governed by PMCR_FORCE_EEE1G and is unvalidated rather than
+		 * unsupported. Leave it out of both bitmaps: lpi_capabilities
+		 * gates on the media speed a rate matching PHY reports, not
+		 * on the speed the MAC runs at.
+		 */
+		config->lpi_capabilities = MAC_100FD | MAC_1000FD;
+		phy_interface_copy(config->lpi_interfaces,
+				   config->supported_interfaces);
+		__clear_bit(PHY_INTERFACE_MODE_2500BASEX,
+			    config->lpi_interfaces);
+
 		/* tx_lpi_timer should be in microseconds. The time units for
 		 * LPI threshold are unspecified.
 		 */
 		config->lpi_timer_default = FIELD_GET(LPI_THRESH_MASK, eeecr);
 	}
-
-	priv->info->mac_port_get_caps(ds, port, config);
 }
 
 static int mt753x_pcs_validate(struct phylink_pcs *pcs,
-- 
2.55.0

[PATCH net v3 2/2] net: ethernet: mtk_eth_soc: populate lpi_interfaces to fix EEE support

[Aleksei Sviridkin]

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. 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.

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>
---

On the netsys v3 switch MAC the xGMII filter empties lpi_interfaces
outright, as PHY_INTERFACE_MODE_INTERNAL is the only interface it
supports. It is a fixed link port with no PHY, so phylink had no EEE to
manage there before this patch either.

Pre-existing and not addressed here: mtk_mac_enable_tx_lpi() programs
MT7531's reset wakeup times (17 for 1 Gbps, 36 for 100 Mbps) whenever
it runs, as its own comment says, so they now apply to every SoC driven
by mtk_phylink_ops once a user enables EEE on an eligible interface.
Those values do not appear to have been confirmed for MT7981, MT7986 or
MT7988.

v2, with the full argument for leaving 2.5 Gbps out:
https://lore.kernel.org/netdev/20260824024117.46154-3-f@lex.la/
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 22 ++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index be3bd025c41a..37a831f73da6 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -4828,7 +4828,7 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
 	phy_interface_t phy_mode;
 	struct phylink *phylink;
 	struct mtk_mac *mac;
-	int id, err;
+	int id, err, i;
 	int txqs = 1;
 	u32 val;
 
@@ -4907,8 +4907,11 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
 	mac->phylink_config.type = PHYLINK_NETDEV;
 	mac->phylink_config.mac_capabilities = MAC_ASYM_PAUSE | MAC_SYM_PAUSE |
 		MAC_10 | MAC_100 | MAC_1000 | MAC_2500FD;
-	mac->phylink_config.lpi_capabilities = MAC_100FD | MAC_1000FD |
-		MAC_2500FD;
+	/* MAC_MCR folds SPEED_2500 onto MAC_MCR_SPEED_1000, so LPI above
+	 * 1 Gbps would be governed by MAC_MCR_EEE1G and is unvalidated
+	 * rather than unsupported.
+	 */
+	mac->phylink_config.lpi_capabilities = MAC_100FD | MAC_1000FD;
 	mac->phylink_config.lpi_timer_default = 1000;
 
 	/* MT7623 gmac0 is now missing its speed-specific PLL configuration
@@ -4966,6 +4969,19 @@ static int mtk_add_mac(struct mtk_eth *eth, struct device_node *np)
 		__set_bit(PHY_INTERFACE_MODE_INTERNAL,
 			  mac->phylink_config.supported_interfaces);
 
+	phy_interface_copy(mac->phylink_config.lpi_interfaces,
+			   mac->phylink_config.supported_interfaces);
+
+	/* The MAC side of 2500BASE-X is never below 2.5 Gbps, not even when
+	 * a rate matching PHY drops the media to 1 Gbps, and
+	 * mtk_mac_enable_tx_lpi() refuses the xGMII modes outright.
+	 */
+	__clear_bit(PHY_INTERFACE_MODE_2500BASEX,
+		    mac->phylink_config.lpi_interfaces);
+	for (i = 0; i < PHY_INTERFACE_MODE_MAX; i++)
+		if (mtk_interface_mode_is_xgmii(eth, i))
+			__clear_bit(i, mac->phylink_config.lpi_interfaces);
+
 	phylink = phylink_create(&mac->phylink_config,
 				 of_fwnode_handle(mac->of_node),
 				 phy_mode, mac_ops);
-- 
2.55.0