netdev - Re: [PATCH net-next 1/3] net: phy: Create sysfs reciprocal links for attached

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Date:   Fri, 26 May 2017 17:46:07 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Woojung.Huh@...rochip.com, netdev@...r.kernel.org
Cc:     davem@...emloft.net, andrew@...n.ch
Subject: Re: [PATCH net-next 1/3] net: phy: Create sysfs reciprocal links for
 attached_dev/phydev

Hi Woojung,

On 05/26/2017 05:43 PM, Woojung.Huh@...rochip.com wrote:
> Hi Florian,
>  
>> OK, so here is what is happening: macb_mii_init() calls macb_mii_probe()
>> and so by the time we call phy_connect_direct(), we have not called
>> register_netdevice() yet, netdev_register_kobject() has not been called
>> either, and so sysfs_create_link() fails....
> I just found same thing.
> Yes, register_netdev() was not called at phy_connect_direct() time. 
> 
>> Let me think about a way to solve that, even though I am leaning towards
>> ignoring the errors from sysfs_create_link() rather than fixing each and
>> every Ethernet driver to make it probe its MII bus *after* calling
>> register_netdevice()....
> Agree.

Thanks, would the following work for you? I don't want to do something
more complex than that, although, if we really wanted to see this
information, we could imagine having netdev_register_kobject() check
whether phydev->dev.kobj is valid, and set the symbolic link at that
point... The problem with that approach is that we are no longer
symetrical within the core PHYLIB code (phy_attach_direct and phy_detach).

Let me know if this works so I can make a formal submission:

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index f84414b8f2ee..daad816ee1d1 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -960,14 +960,20 @@ int phy_attach_direct(struct net_device *dev,
struct phy_device *phydev,

        phydev->attached_dev = dev;
        dev->phydev = phydev;
+
+       /* Some Ethernet drivers try to connect to a PHY device before
+        * calling register_netdevice(). register_netdevice() does
ultimately
+        * lead to netdev_register_kobject() which would do the
dev->dev.kobj
+        * initialization. Here we explicitly ignore those particular errors
+        */
        err = sysfs_create_link(&phydev->mdio.dev.kobj, &dev->dev.kobj,
                                "attached_dev");
-       if (err)
+       if (err && err != -ENOENT)
                goto error;

        err = sysfs_create_link(&dev->dev.kobj, &phydev->mdio.dev.kobj,
                                "phydev");
-       if (err)
+       if (err && err != -ENOENT)
                goto error;

        phydev->dev_flags = flags;
-- 
Florian