netdev - Re: [PATCH v1 1/1] net: phy: micrel: Add workaround for incomplete autonegotiation

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Date: Wed, 3 Jan 2024 02:27:02 +0100
From: Andrew Lunn <andrew@...n.ch>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: Asmaa Mnebhi <asmaa@...dia.com>, davem@...emloft.net,
	netdev@...r.kernel.org, davthompson@...dia.com
Subject: Re: [PATCH v1 1/1] net: phy: micrel: Add workaround for incomplete
 autonegotiation

On Tue, Jan 02, 2024 at 06:45:17PM +0000, Russell King (Oracle) wrote:
> On Tue, Dec 26, 2023 at 09:19:03AM -0500, Asmaa Mnebhi wrote:
> > +	/* KSZ9031's autonegotiation takes normally 4-5 seconds to complete.
> > +	 * Occasionally it fails to complete autonegotiation. The workaround is
> > +	 * to restart it.
> > +	 */
> > +        if (phydev->autoneg == AUTONEG_ENABLE) {
> > +		while (timeout) {
> > +			if (phy_aneg_done(phydev))
> > +				break;
> > +			mdelay(1000);
> > +			timeout--;
> > +		};
> 
> Extra needless ;
> 
> Also.. ouch! This means we end up holding phydev->lock for up to ten
> seconds, which prevents anything else happening with phylib during
> that time. Not sure I can see a good way around that though. Andrew?

Is there any status registers which indicate energy detection? No
point doing retries if there is no sign of a link partner.

I would also suggest moving the timeout into a driver private data
structure, and rely on phylib polling the PHY once per second and
restart autoneg from that. That will avoid holding the lock for a long
time.

	Andrew