linux-kernel - Re: [PATCH 1/3] net: macb: fix for fixed-link mode

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Date:   Mon, 9 Dec 2019 11:26:15 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Milind Parab <mparab@...ence.com>
Cc:     nicolas.nerre@...rochip.com, andrew@...n.ch,
        antoine.tenart@...tlin.com, f.fainelli@...il.com,
        davem@...emloft.net, netdev@...r.kernel.org, hkallweit1@...il.com,
        linux-kernel@...r.kernel.org, dkangude@...ence.com,
        a.fatoum@...gutronix.de, brad.mouring@...com, pthombar@...ence.com
Subject: Re: [PATCH 1/3] net: macb: fix for fixed-link mode

On Mon, Dec 09, 2019 at 11:14:21AM +0000, Milind Parab wrote:
> This patch fix the issue with fixed link. With fixed-link
> device opening fails due to macb_phylink_connect not
> handling fixed-link mode, in which case no MAC-PHY connection
> is needed and phylink_connect return success (0), however
> in current driver attempt is made to search and connect to
> PHY even for fixed-link.
> 
> Signed-off-by: Milind Parab <mparab@...ence.com>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 9c767ee252ac..6b68ef34ab19 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -615,17 +615,13 @@ static int macb_phylink_connect(struct macb *bp)
>  {
>  	struct net_device *dev = bp->dev;
>  	struct phy_device *phydev;
> +	struct device_node *dn = bp->pdev->dev.of_node;
>  	int ret;
>  
> -	if (bp->pdev->dev.of_node &&
> -	    of_parse_phandle(bp->pdev->dev.of_node, "phy-handle", 0)) {
> -		ret = phylink_of_phy_connect(bp->phylink, bp->pdev->dev.of_node,
> -					     0);
> -		if (ret) {
> -			netdev_err(dev, "Could not attach PHY (%d)\n", ret);
> -			return ret;
> -		}
> -	} else {
> +	if (dn)
> +		ret = phylink_of_phy_connect(bp->phylink, dn, 0);
> +
> +	if (!dn || (ret && !of_parse_phandle(dn, "phy-handle", 0))) {

Hi,

If of_parse_phandle() returns non-null, the device_node it returns will
have its reference count increased by one.  That reference needs to be
put.

I assume you're trying to determine whether phylink_of_phy_connect()
failed because of a missing phy-handle rather than of_phy_attach()
failing?  Maybe those two failures ought to be distinguished by errno
return value?

of_phy_attach() may fail due to of_phy_find_device() failing to find
the PHY, or phy_attach_direct() failing.  We could switch from using
of_phy_attach(), to using of_phy_find_device() directly so we can then
propagate phy_attach_direct()'s error code back, rather than losing it.
That would then leave the case of of_phy_find_device() failure to be
considered in terms of errno return value.

>  		phydev = phy_find_first(bp->mii_bus);
>  		if (!phydev) {
>  			netdev_err(dev, "no PHY found\n");
> @@ -638,6 +634,9 @@ static int macb_phylink_connect(struct macb *bp)
>  			netdev_err(dev, "Could not attach to PHY (%d)\n", ret);
>  			return ret;
>  		}
> +	} else if (ret) {
> +		netdev_err(dev, "Could not attach PHY (%d)\n", ret);
> +		return ret;
>  	}
>  
>  	phylink_start(bp->phylink);
> -- 
> 2.17.1
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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