netdev - Re: [PATCH net 1/1] net: phy: marvell: add link status check before enabling phy loopback

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Date:   Thu, 25 Aug 2022 15:26:57 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Aminuddin Jamaluddin <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>,
        Mohammad Athari Bin Ismail <mohammad.athari.ismail@...el.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, tee.min.tan@...el.com,
        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?

Have you tested this with the cable unplugged?

> +			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.

	Andrew