[net,v2,0/2] net: fec: Fixes to suspend / resume with mac_managed_pm

Message

John Ernberg Feb. 29, 2024, 10:53 a.m. UTC

Since the introduction of mac_managed_pm in the FEC driver there were some
discrepancies regarding power management of the PHY.

This failed on our board that has a permanently powered Microchip LAN8700R
attached to the FEC. Although the root cause of the failure can be traced
back to f166f890c8f0 ("net: ethernet: fec: Replace interrupt driven MDIO
with polled IO") and probably even before that, we only started noticing
the problem going from 5.10 to 6.1.

Since 557d5dc83f68 ("net: fec: use mac-managed PHY PM") is actually a fix
to most of the power management sequencing problems that came with power
managing the MDIO bus which for the FEC meant adding a race with FEC
resume (and phy_start() if netif was running) and PHY resume.

That it worked before for us was probably just luck...

Thanks to Wei's response to my report at [1] I was able to pick up his
patch and start honing in on the remaining missing details.

[1]: https://lore.kernel.org/netdev/[e-mail]/

v2:
 - Completely different approach that should be much more correct
   (Wei Fang, Jakub Kucinski)
 - Re-target to net tree, because I have fixes tags now

v1: https://lore.kernel.org/netdev/[e-mail]/

John Ernberg (1):
  net: fec: Suspend and resume the PHY

Wei Fang (1):
  net: fec: Set mac_managed_pm during probe

 drivers/net/ethernet/freescale/fec_main.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)