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From: John Ernberg <john.ernberg@actia.se>
To: Wei Fang <wei.fang@nxp.com>
CC: Shenwei Wang <shenwei.wang@nxp.com>, Clark Wang <xiaoning.wang@nxp.com>,
	NXP Linux Team <linux-imx@nxp.com>, "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, "Paolo
 Abeni" <pabeni@redhat.com>, Heiner Kallweit <hkallweit1@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, John Ernberg
	<john.ernberg@actia.se>
Subject: [PATCH net v2 0/2] net: fec: Fixes to suspend / resume with
 mac_managed_pm
Thread-Topic: [PATCH net v2 0/2] net: fec: Fixes to suspend / resume with
 mac_managed_pm
Thread-Index: AQHaav1+R0XAsBAPyEuuMQx/2+BDqQ==
Date: Thu, 29 Feb 2024 10:53:14 +0000
Message-ID: <20240229105256.2903095-1-john.ernberg@actia.se>
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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/1f45bdbe-eab1-4e59-8f24-add177590d27@ac=
tia.se/

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/20240212105010.2258421-1-john.ernberg@ac=
tia.se/

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(-)

--=20
2.43.0