linux-kernel - Re: [net-next RFC PATCH 04/14] net: phy: add initial support for PHY package in DT

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Date:   Wed, 22 Nov 2023 19:15:06 +0100
From:   Christian Marangi <ansuelsmth@...il.com>
To:     Simon Horman <horms@...nel.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Florian Fainelli <florian.fainelli@...adcom.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Daniel Golle <daniel@...rotopia.org>,
        Qingfang Deng <dqfext@...il.com>,
        SkyLake Huang <SkyLake.Huang@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        David Epping <david.epping@...singlinkelectronics.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
        Harini Katakam <harini.katakam@....com>,
        Robert Marko <robert.marko@...tura.hr>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [net-next RFC PATCH 04/14] net: phy: add initial support for PHY
 package in DT

On Wed, Nov 22, 2023 at 10:52:43AM +0000, Simon Horman wrote:
> On Mon, Nov 20, 2023 at 02:50:31PM +0100, Christian Marangi wrote:
> > Add initial support for PHY package in DT.
> > 
> > Make it easier to define PHY package and describe the global PHY
> > directly in DT by refereincing them by phandles instead of custom
> > functions in each PHY driver.
> > 
> > Each PHY in a package needs to be defined in a dedicated node in the
> > mdio node. This dedicated node needs to have the compatible set to
> > "ethernet-phy-package" and define "global-phys" and "#global-phy-cells"
> > respectively to a list of phandle to the global phy to define for the
> > PHY package and 0 for cells as the phandle won't take any args.
> > 
> > With this defined, the generic PHY probe will join each PHY in this
> > dedicated node to the package.
> > 
> > PHY driver MUST set the required global PHY count in
> > .phy_package_global_phy_num to correctly verify that DT define the
> > correct number of phandle to the required global PHY.
> > 
> > mdio_bus.c and of_mdio.c is updated to now support and parse also
> > PHY package subnote that have the compatible "phy-package".
> > 
> > Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> 
> Hi Christian,
> 
> I was a little hasty in hitting send on my previous message.
> Please find some more minor feedback from my side below.
>

Thanks a lot for the initial review and sorry for the various warning
you had to write about it. I know this was a new concept and that I had
to discuss a lot about the DT structure so I was a bit relaxed in
releasing OF node. Will handle all of them in v2. Again thanks! 

> ...
> 
> > diff --git a/drivers/net/mdio/of_mdio.c b/drivers/net/mdio/of_mdio.c
> > index 64ebcb6d235c..bb910651118f 100644
> > --- a/drivers/net/mdio/of_mdio.c
> > +++ b/drivers/net/mdio/of_mdio.c
> > @@ -139,6 +139,44 @@ bool of_mdiobus_child_is_phy(struct device_node *child)
> >  }
> >  EXPORT_SYMBOL(of_mdiobus_child_is_phy);
> >  
> > +static int __of_mdiobus_parse_phys(struct mii_bus *mdio, struct device_node *np,
> > +				   bool *scanphys)
> > +{
> > +	struct device_node *child;
> > +	int addr, rc;
> > +
> > +	/* Loop over the child nodes and register a phy_device for each phy */
> > +	for_each_available_child_of_node(np, child) {
> > +		if (of_device_is_compatible(child, "ethernet-phy-package")) {
> > +			rc = __of_mdiobus_parse_phys(mdio, child, scanphys);
> > +			if (rc && rc != -ENODEV)
> > +				return rc;
> 
> for_each_available_child_of_node() makes calls to of_node_get() and
> of_node_put(), so when jumping out of a loop it is necessary to call
> of_node_put(), in this case of_node_put(child).
> 
> As flagged by Coccinelle.
> 
> Also flagged in of_mdiobus_find_phy() both before and after this patch.
> 
> > +
> > +			continue;
> > +		}
> > +
> > +		addr = of_mdio_parse_addr(&mdio->dev, child);
> > +		if (addr < 0) {
> > +			*scanphys = true;
> > +			continue;
> > +		}
> > +
> > +		if (of_mdiobus_child_is_phy(child))
> > +			rc = of_mdiobus_register_phy(mdio, child, addr);
> > +		else
> > +			rc = of_mdiobus_register_device(mdio, child, addr);
> > +
> > +		if (rc == -ENODEV)
> > +			dev_err(&mdio->dev,
> > +				"MDIO device at address %d is missing.\n",
> > +				addr);
> > +		else if (rc)
> > +			return rc;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  /**
> >   * __of_mdiobus_register - Register mii_bus and create PHYs from the device tree
> >   * @mdio: pointer to mii_bus structure
> > @@ -180,25 +218,9 @@ int __of_mdiobus_register(struct mii_bus *mdio, struct device_node *np,
> >  		return rc;
> >  
> >  	/* Loop over the child nodes and register a phy_device for each phy */
> > -	for_each_available_child_of_node(np, child) {
> > -		addr = of_mdio_parse_addr(&mdio->dev, child);
> > -		if (addr < 0) {
> > -			scanphys = true;
> > -			continue;
> > -		}
> > -
> > -		if (of_mdiobus_child_is_phy(child))
> > -			rc = of_mdiobus_register_phy(mdio, child, addr);
> > -		else
> > -			rc = of_mdiobus_register_device(mdio, child, addr);
> > -
> > -		if (rc == -ENODEV)
> > -			dev_err(&mdio->dev,
> > -				"MDIO device at address %d is missing.\n",
> > -				addr);
> > -		else if (rc)
> > -			goto unregister;
> > -	}
> > +	rc = __of_mdiobus_parse_phys(mdio, np, &scanphys);
> > +	if (rc)
> > +		goto unregister;
> 
> Jumping to unregister will call of_node_put(child),
> however child appears to be uninitialised here.
> 
> Flagged by clang-16 W=1 build, and Smatch.
> 
> >  
> >  	if (!scanphys)
> >  		return 0;
> 
> ...

-- 
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