netdev - Re: [PATCH] net: fec: Fix phy_device lookup for phy_reset_after_clk

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Message-ID: <20201008174619.282b3482@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Thu, 8 Oct 2020 17:46:19 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Marek Vasut <marex@...x.de>
Cc:     Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
        Christoph Niedermaier <cniedermaier@...electronics.com>,
        "David S . Miller" <davem@...emloft.net>,
        NXP Linux Team <linux-imx@....com>,
        Richard Leitner <richard.leitner@...data.com>,
        Shawn Guo <shawnguo@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH] net: fec: Fix phy_device lookup for
 phy_reset_after_clk_enable()

On Wed, 7 Oct 2020 00:02:42 +0200 Marek Vasut wrote:
> On 10/6/20 11:09 PM, Florian Fainelli wrote:
> > On 10/6/2020 1:20 PM, Marek Vasut wrote:  
> >> The phy_reset_after_clk_enable() is always called with ndev->phydev,
> >> however that pointer may be NULL even though the PHY device instance
> >> already exists and is sufficient to perform the PHY reset.
> >>
> >> If the PHY still is not bound to the MAC, but there is OF PHY node
> >> and a matching PHY device instance already, use the OF PHY node to
> >> obtain the PHY device instance, and then use that PHY device instance
> >> when triggering the PHY reset.
> >>
> >> Fixes: 1b0a83ac04e3 ("net: fec: add phy_reset_after_clk_enable()
> >> support")
> >> Signed-off-by: Marek Vasut <marex@...x.de>

> >> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> >> b/drivers/net/ethernet/freescale/fec_main.c
> >> index 2d5433301843..5a4b20941aeb 100644
> >> --- a/drivers/net/ethernet/freescale/fec_main.c
> >> +++ b/drivers/net/ethernet/freescale/fec_main.c
> >> @@ -1912,6 +1912,24 @@ static int fec_enet_mdio_write(struct mii_bus
> >> *bus, int mii_id, int regnum,
> >>       return ret;
> >>   }
> >>   +static void fec_enet_phy_reset_after_clk_enable(struct net_device
> >> *ndev)
> >> +{
> >> +    struct fec_enet_private *fep = netdev_priv(ndev);
> >> +    struct phy_device *phy_dev = ndev->phydev;
> >> +
> >> +    /*
> >> +     * If the PHY still is not bound to the MAC, but there is
> >> +     * OF PHY node and a matching PHY device instance already,
> >> +     * use the OF PHY node to obtain the PHY device instance,
> >> +     * and then use that PHY device instance when triggering
> >> +     * the PHY reset.
> >> +     */
> >> +    if (!phy_dev && fep->phy_node)
> >> +        phy_dev = of_phy_find_device(fep->phy_node);  
> > 
> > Don't you need to put the phy_dev reference at some point?  
> 
> Probably, yes.
> 
> But first, does this approach and this patch even make sense ?
> I mean, it fixes my problem, but is this right ?

Can you describe your problem in detail?

To an untrained eye this looks pretty weird.