netdev - Re: [PATCH 1/1] net: phy: dp83867: Disable IRQs on suspend

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Message-ID: <2156693.PYKUYFuaPT@steina-w>
Date:   Thu, 09 Mar 2023 11:52:06 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH 1/1] net: phy: dp83867: Disable IRQs on suspend

Hi Andrew,

thanks for the response.

Am Dienstag, 28. Februar 2023, 16:05:27 CET schrieb Andrew Lunn:
> > +static int dp83867_suspend(struct phy_device *phydev)
> > +{
> > +	/* Disable PHY Interrupts */
> > +	if (phy_interrupt_is_valid(phydev)) {
> > +		phydev->interrupts = PHY_INTERRUPT_DISABLED;
> > +		if (phydev->drv->config_intr)
> > +			phydev->drv->config_intr(phydev);
> 
> It seems odd going via phydev->drv inside the driver to call functions
> which are also inside the driver. Why do you not directly call
> dp83867_config_intr()?

I was going the same way kszphy_suspend() (micrel.c) is doing. Maybe that was 
a bad example and it should be changed as well.
There should be no reason to not call dp83867_config_intr directly.

> > +static int dp83867_resume(struct phy_device *phydev)
> > +{
> > +	genphy_resume(phydev);
> > +
> > +	/* Enable PHY Interrupts */
> > +	if (phy_interrupt_is_valid(phydev)) {
> > +		phydev->interrupts = PHY_INTERRUPT_ENABLED;
> > +		if (phydev->drv->config_intr)
> > +			phydev->drv->config_intr(phydev);
> > +	}
> 
> Is there a race here? Say the PHY is in a fixed mode, not
> autoneg. Could it be, that as soon as you clear the power down bit in
> genphy_resume() it signals a link up interrupt? dp83867_config_intr()
> then acknowledged and clears that interrupt, before enabling the
> interrupt, so the link up event never gets passed to phylib? Maybe the
> order needs reversing here?

Yes, your explanation sounds reasonable, unfortunately I can't test this right 
now, as there is some other error regarding PMIC power domains.
If your reasoning is true then micrel.c has the same issue.

Best regards,
Alexander
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