linux-kernel - RE: [PATCH net 1/1] net: phy: marvell: add link status check before enabling phy loopback

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Message-ID: <DM6PR11MB43480C1D3526031F79592A7F81799@DM6PR11MB4348.namprd11.prod.outlook.com>
Date:   Tue, 30 Aug 2022 07:51:46 +0000
From:   "Jamaluddin, Aminuddin" <aminuddin.jamaluddin@...el.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>,
        "Ismail, Mohammad Athari" <mohammad.athari.ismail@...el.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "Tan, Tee Min" <tee.min.tan@...el.com>,
        "Zulkifli, Muhammad Husaini" <muhammad.husaini.zulkifli@...el.com>
Subject: RE: [PATCH net 1/1] net: phy: marvell: add link status check before
 enabling phy loopback



> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: Thursday, 25 August, 2022 9:27 PM
> To: Jamaluddin, Aminuddin <aminuddin.jamaluddin@...el.com>
> 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>; Ismail, Mohammad Athari
> <mohammad.athari.ismail@...el.com>; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; stable@...r.kernel.org; Tan, Tee Min
> <tee.min.tan@...el.com>; Zulkifli, Muhammad Husaini
> <muhammad.husaini.zulkifli@...el.com>
> Subject: Re: [PATCH net 1/1] net: phy: marvell: add link status check before
> enabling phy loopback
> 
> > @@ -2015,14 +2016,23 @@ static int m88e1510_loopback(struct
> phy_device *phydev, bool enable)
> >  		if (err < 0)
> >  			return err;
> >
> > -		/* FIXME: Based on trial and error test, it seem 1G need to
> have
> > -		 * delay between soft reset and loopback enablement.
> > -		 */
> > -		if (phydev->speed == SPEED_1000)
> > -			msleep(1000);
> > +		if (phydev->speed == SPEED_1000) {
> > +			err = phy_read_poll_timeout(phydev, MII_BMSR,
> val, val & BMSR_LSTATUS,
> > +						    PHY_LOOP_BACK_SLEEP,
> > +
> PHY_LOOP_BACK_TIMEOUT, true);
> 
> Is this link with itself?
 
Its required cabled plug in, back to back connection.

> 
> Have you tested this with the cable unplugged?

Yes we have and its expected to have the timeout. But the self-test required the link
to be up first before it can be run.

> 
> > +			if (err)
> > +				return err;
> 
> I'm just trying to ensure we don't end up here with -ETIMEDOUT.
> 
> >
> > +#define PHY_LOOP_BACK_SLEEP	1000000
> > +#define PHY_LOOP_BACK_TIMEOUT	8000000
> 
> The kernel seems to be pretty consistent in having loopback as one word.

Noted will update in v2.

> 
> 	Andrew