5.15-stable review patch. If anyone has any objections, please let me know.
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From: Wei Fang wei.fang@nxp.com
[ Upstream commit cbc17e7802f5de37c7c262204baadfad3f7f99e5 ]
Setting mac_managed_pm during interface up is too late.
In situations where the link is not brought up yet and the system suspends the regular PHY power management will run. Since the FEC ETHEREN control bit is cleared (automatically) on suspend the controller is off in resume. When the regular PHY power management resume path runs in this context it will write to the MII_DATA register but nothing will be transmitted on the MDIO bus.
This can be observed by the following log:
fec 5b040000.ethernet eth0: MDIO read timeout Microchip LAN87xx T1 5b040000.ethernet-1:04: PM: dpm_run_callback(): mdio_bus_phy_resume+0x0/0xc8 returns -110 Microchip LAN87xx T1 5b040000.ethernet-1:04: PM: failed to resume: error -110
The data written will however remain in the MII_DATA register.
When the link later is set to administrative up it will trigger a call to fec_restart() which will restore the MII_SPEED register. This triggers the quirk explained in f166f890c8f0 ("net: ethernet: fec: Replace interrupt driven MDIO with polled IO") causing an extra MII_EVENT.
This extra event desynchronizes all the MDIO register reads, causing them to complete too early. Leading all reads to read as 0 because fec_enet_mdio_wait() returns too early.
When a Microchip LAN8700R PHY is connected to the FEC, the 0 reads causes the PHY to be initialized incorrectly and the PHY will not transmit any ethernet signal in this state. It cannot be brought out of this state without a power cycle of the PHY.
Fixes: 557d5dc83f68 ("net: fec: use mac-managed PHY PM") Closes: https://lore.kernel.org/netdev/1f45bdbe-eab1-4e59-8f24-add177590d27@actia.se... Signed-off-by: Wei Fang wei.fang@nxp.com [jernberg: commit message] Signed-off-by: John Ernberg john.ernberg@actia.se Link: https://lore.kernel.org/r/20240328155909.59613-2-john.ernberg@actia.se Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/freescale/fec_main.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 6662c0013959e..972808777f308 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -2132,8 +2132,6 @@ static int fec_enet_mii_probe(struct net_device *ndev) fep->link = 0; fep->full_duplex = 0;
- phy_dev->mac_managed_pm = true; - phy_attached_info(phy_dev);
return 0; @@ -2145,10 +2143,12 @@ static int fec_enet_mii_init(struct platform_device *pdev) struct net_device *ndev = platform_get_drvdata(pdev); struct fec_enet_private *fep = netdev_priv(ndev); bool suppress_preamble = false; + struct phy_device *phydev; struct device_node *node; int err = -ENXIO; u32 mii_speed, holdtime; u32 bus_freq; + int addr;
/* * The i.MX28 dual fec interfaces are not equal. @@ -2258,6 +2258,13 @@ static int fec_enet_mii_init(struct platform_device *pdev) goto err_out_free_mdiobus; of_node_put(node);
+ /* find all the PHY devices on the bus and set mac_managed_pm to true */ + for (addr = 0; addr < PHY_MAX_ADDR; addr++) { + phydev = mdiobus_get_phy(fep->mii_bus, addr); + if (phydev) + phydev->mac_managed_pm = true; + } + mii_cnt++;
/* save fec0 mii_bus */