netdev - Problem with PHY state machine when using interrupts

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Date:   Mon, 24 Jul 2017 13:07:47 +0200
From:   Mason <slash.tmp@...e.fr>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>, Mans Rullgard <mans@...sr.com>
Cc:     netdev <netdev@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Problem with PHY state machine when using interrupts

Hello,

When I set the link down via 'ip link set eth0 down'
(as opposed to pulling the Ethernet cable) things don't happen as expected:

The driver's adjust_link() callback is never called, and doesn't
get a chance make some required changes. And when I set the link
up again, there is no network connectivity.

I get this problem only if I enable interrupts on my PHY.
If I use polling, things work as expected.

When I set the link down, devinet_ioctl() eventually calls
ndo_set_rx_mode() and ndo_stop()

In ndo_stop() the driver calls
phy_stop(phydev);
which disables interrupts and sets the state to HALTED.

In phy_state_machine()
the PHY_HALTED case does call the adjust_link() callback:

		if (phydev->link) {
			phydev->link = 0;
			netif_carrier_off(phydev->attached_dev);
			phy_adjust_link(phydev);
			do_suspend = true;
		}

But it's not called when I use interrupts...

Perhaps because there are no interrupts generated?
Or even if there were, they have been turned off by phy_stop?

Basically, it seems like when I use interrupts,
the phy_state_machine() is not called on link down,
which breaks the MAC driver's expectations.

Am I barking up the wrong tree?

Regards.