Re: [PATCH] net: phy: Don't disable irqs on shutdown if WoL is enabled

Andrew Lunn
2023-08-09T16:22:14Z

> Thinking about this, I wonder whether we could solve your issue by
> disabling interrupts when the PHY is probed, rather than disabling
> them on shutdown - something like this? (not build tested)
>
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index 3e9909b30938..4d1a37487923 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -3216,6 +3216,8 @@ static int phy_probe(struct device *dev)
> goto out;
> }
>
> + phy_disable_interrupts(phydev);
> +
> /* Start out supporting everything. Eventually,
> * a controller will attach, and may modify one
> * or both of these values

At some point, the interrupt is going to be enabled again. And then
the WoL interrupt will fire. I think some PHY drivers actually need to
see that WoL interrupt. e.g. the marvell driver has this comment:

static int m88e1318_set_wol(struct phy_device *phydev,
struct ethtool_wolinfo *wol)
{
....
/* If WOL event happened once, the LED[2] interrupt pin
* will not be cleared unless we reading the interrupt status
* register. If interrupts are in use, the normal interrupt
* handling will clear the WOL event. Clear the WOL event
* before enabling it if !phy_interrupt_is_valid()
*/

So it seems like just probing the marvell PHY is not enough to clear
the WoL interrupt.

Can we be sure that the other PHY has reached a state it can handle
and clear an interrupt when we come to enable the interrupt? I think
not, especially in cases like NFS root, where the interface will be
put into use as soon as it exists, maybe before the other interface
has probed.

Andrew