Re: [PATCH net-next 3/4] fec: add FIXME to move 'mac_managed_pm' to probe

From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: Wei Fang <wei.fang@nxp.com>,
	"linux-renesas-soc@vger.kernel.org" 
	<linux-renesas-soc@vger.kernel.org>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	Shenwei Wang <shenwei.wang@nxp.com>,
	Clark Wang <xiaoning.wang@nxp.com>,
	dl-linux-imx <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>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next 3/4] fec: add FIXME to move 'mac_managed_pm' to probe
Date: Thu, 16 Mar 2023 09:02:17 +0100	[thread overview]
Message-ID: <ZBLNCYgeTtNBSaMi@ninjato> (raw)
In-Reply-To: <ZBFzVjaRjcITP0bA@ninjato>

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> Yes, I will resend the series as RFC with more explanations.

Because I was able to fix SMSC myself, I'll just describe the procedure
here:

1) apply this debug patch:

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 1b2e253fce75..7b79c5979486 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -310,6 +310,8 @@ static __maybe_unused int mdio_bus_phy_suspend(struct device *dev)
 	if (phydev->mac_managed_pm)
 		return 0;
 
+printk(KERN_INFO "****** MDIO suspend\n");
+
 	/* Wakeup interrupts may occur during the system sleep transition when
 	 * the PHY is inaccessible. Set flag to postpone handling until the PHY
 	 * has resumed. Wait for concurrent interrupt handler to complete.

2) boot the device without bringing the interface (and thus the PHY) up.
   Bringing it down after it was up is not the same! It is important
   that it was never up before.

3) do a suspend-to-ram/resume cycle

4) your log should show the above debug message. If not, I was wrong

5) If yes, apply a similar fix to the one I did for the Renesas drivers
   in this series

6) suspend/resume should not show the debug message anymore

7) test for regressions and send out :)

I hope this was understandable. If not, feel free to ask.

Happy hacking,

   Wolfram


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