netdev - Re: [PATCH net] net: phy: fix phy_uses_state

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Message-ID: <aLVivd71G4P4pU0U@shell.armlinux.org.uk>
Date: Mon, 1 Sep 2025 10:09:17 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Vladimir Oltean <vladimir.oltean@....com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net] net: phy: fix phy_uses_state_machine()

On Mon, Sep 01, 2025 at 11:42:25AM +0300, Vladimir Oltean wrote:
> On Sun, Aug 31, 2025 at 05:38:11PM +0100, Russell King (Oracle) wrote:
> > phydev->phy_link_change is initialised by phy_attach_direct(), and
> > overridden by phylink. This means that a never-connected PHY will
> > have phydev->phy_link_change set to NULL, which causes
> > phy_uses_state_machine() to return true. This is incorrect.
> 
> Another nitpick regarding phrasing here: the never-connected PHY doesn't
> _cause_ phy_uses_state_machine() to return true. It returns true _in
> spite_ of the PHY never being connected: the non-NULL quality of
> phydev->phy_link_change is not something that phy_uses_state_machine()
> tests for.

No. What I'm saying is that if phydev->phy_link_change is set to NULL,
_this_ causes phy_uses_state_machine() to return true and that
behaviour incorrect.

The first part is describing _when_ phydev->phy_link_change is set to
NULL.

It is not saying that a never-connected PHY directly causes
phy_uses_state_machine() to return true.

I think my phrasing of this is totally fine, even re-reading it now.

-- 
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