netdev - Re: [PATCH net-next] mdio: mdiobus: setup of

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Message-ID: <20210615172444.dirudehe3vzis2kw@skbuf>
Date:   Tue, 15 Jun 2021 20:24:44 +0300
From:   Ioana Ciornei <ciorneiioana@...il.com>
To:     "Russell King (Oracle)" <linux@...linux.org.uk>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        calvin.johnson@....nxp.com, andrew@...n.ch, hkallweit1@...il.com,
        Ioana Ciornei <ioana.ciornei@....com>
Subject: Re: [PATCH net-next] mdio: mdiobus: setup of_node for the MDIO device

On Tue, Jun 15, 2021 at 06:13:31PM +0100, Russell King (Oracle) wrote:
> On Tue, Jun 15, 2021 at 06:44:01PM +0300, Ioana Ciornei wrote:
> > From: Ioana Ciornei <ioana.ciornei@....com>
> > 
> > By mistake, the of_node of the MDIO device was not setup in the patch
> > linked below. As a consequence, any PHY driver that depends on the
> > of_node in its probe callback was not be able to successfully finish its
> > probe on a PHY, thus the Generic PHY driver was used instead.
> > 
> > Fix this by actually setting up the of_node.
> > 
> > Fixes: bc1bee3b87ee ("net: mdiobus: Introduce fwnode_mdiobus_register_phy()")
> > Signed-off-by: Ioana Ciornei <ioana.ciornei@....com>
> > ---
> >  drivers/net/mdio/fwnode_mdio.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> > index e96766da8de4..283ddb1185bd 100644
> > --- a/drivers/net/mdio/fwnode_mdio.c
> > +++ b/drivers/net/mdio/fwnode_mdio.c
> > @@ -65,6 +65,7 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
> >  	 * can be looked up later
> >  	 */
> >  	fwnode_handle_get(child);
> > +	phy->mdio.dev.of_node = to_of_node(child);
> >  	phy->mdio.dev.fwnode = child;
> 
> Yes, this is something that was missed, but let's first look at what
> other places to when setting up a device:
> 
>         pdev->dev.fwnode = pdevinfo->fwnode;
>         pdev->dev.of_node = of_node_get(to_of_node(pdev->dev.fwnode));
>         pdev->dev.of_node_reused = pdevinfo->of_node_reused;
> 
>         dev->dev.of_node = of_node_get(np);
>         dev->dev.fwnode = &np->fwnode;
> 
>         dev->dev.of_node = of_node_get(node);
>         dev->dev.fwnode = &node->fwnode;
> 
> That seems to be pretty clear that an of_node_get() is also needed.
> 

I'm not convinced that an of_node_get() is needed besides the
fwnode_handle_get() call that's already there.

The fwnode_handle_get() will call the get callback for that particular
fwnode_handle. When we are in the OF case, the of_fwnode_get() will be
invoked which in turn does of_node_get().

Am I missing something here?

Ioana