linux-kernel - Re: [PATCH net-next] net: dsa: mt7530: support OF-based registration of switch MDIO bus

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Date: Mon, 8 Jan 2024 15:14:45 +0300
From: Arınç ÜNAL <arinc.unal@...nc9.com>
To: Vladimir Oltean <olteanv@...il.com>
Cc: Simon Horman <horms@...nel.org>, Daniel Golle <daniel@...rotopia.org>,
 Landen Chao <Landen.Chao@...iatek.com>, DENG Qingfang <dqfext@...il.com>,
 Sean Wang <sean.wang@...iatek.com>, Andrew Lunn <andrew@...n.ch>,
 Florian Fainelli <f.fainelli@...il.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 David Bauer <mail@...id-bauer.net>, mithat.guner@...ont.com,
 erkin.bozoglu@...ont.com, Luiz Angelo Daros de Luca <luizluca@...il.com>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next] net: dsa: mt7530: support OF-based registration
 of switch MDIO bus

On 8.01.2024 14:00, Vladimir Oltean wrote:
> On Mon, Jan 08, 2024 at 01:22:18PM +0300, Arınç ÜNAL wrote:
>>>> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
>>>> index 391c4dbdff42..39d7e7ad7154 100644
>>>> --- a/drivers/net/dsa/mt7530.c
>>>> +++ b/drivers/net/dsa/mt7530.c
>>>> @@ -2153,17 +2153,25 @@ mt7530_free_irq(struct mt7530_priv *priv)
>>>>    static int
>>>>    mt7530_setup_mdio(struct mt7530_priv *priv)
>>>>    {
>>>> +	struct device_node *mnp, *np = priv->dev->of_node;
>>>>    	struct dsa_switch *ds = priv->ds;
>>>>    	struct device *dev = priv->dev;
>>>>    	struct mii_bus *bus;
>>>>    	static int idx;
>>>> -	int ret;
>>>> +	int ret = 0;
>>>> +
>>>> +	mnp = of_get_child_by_name(np, "mdio");
>>>> +
>>>> +	if (mnp && !of_device_is_available(mnp))
>>>> +		goto out;
>>>
>>> nit: I think it would easier on the eyes to simply
>>>
>>> 		return 0;
> 
> Actually "return 0" leaks "mnp". An of_node_put() is needed.

I realised that I also miss these:

- run of_node_put(mnp) if bus = devm_mdiobus_alloc(dev) fails
- don't run mt7530_free_mdio_irq if MDIO bus is described on OF

Please let me know if this addresses everything:

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 391c4dbdff42..cf2ff7680c15 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2146,24 +2146,40 @@ mt7530_free_irq_common(struct mt7530_priv *priv)
  static void
  mt7530_free_irq(struct mt7530_priv *priv)
  {
-	mt7530_free_mdio_irq(priv);
+	struct device_node *mnp, *np = priv->dev->of_node;
+
+	mnp = of_get_child_by_name(np, "mdio");
+	if (!mnp)
+		mt7530_free_mdio_irq(priv);
+	of_node_put(mnp);
+
  	mt7530_free_irq_common(priv);
  }
  
  static int
  mt7530_setup_mdio(struct mt7530_priv *priv)
  {
+	struct device_node *mnp, *np = priv->dev->of_node;
  	struct dsa_switch *ds = priv->ds;
  	struct device *dev = priv->dev;
  	struct mii_bus *bus;
  	static int idx;
-	int ret;
+	int ret = 0;
+
+	mnp = of_get_child_by_name(np, "mdio");
+
+	if (mnp && !of_device_is_available(mnp))
+		goto out;
  
  	bus = devm_mdiobus_alloc(dev);
-	if (!bus)
-		return -ENOMEM;
+	if (!bus) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (!mnp)
+		ds->user_mii_bus = bus;
  
-	ds->user_mii_bus = bus;
  	bus->priv = priv;
  	bus->name = KBUILD_MODNAME "-mii";
  	snprintf(bus->id, MII_BUS_ID_SIZE, KBUILD_MODNAME "-%d", idx++);
@@ -2174,16 +2190,18 @@ mt7530_setup_mdio(struct mt7530_priv *priv)
  	bus->parent = dev;
  	bus->phy_mask = ~ds->phys_mii_mask;
  
-	if (priv->irq)
+	if (priv->irq && !mnp)
  		mt7530_setup_mdio_irq(priv);
  
-	ret = devm_mdiobus_register(dev, bus);
+	ret = devm_of_mdiobus_register(dev, bus, mnp);
  	if (ret) {
  		dev_err(dev, "failed to register MDIO bus: %d\n", ret);
-		if (priv->irq)
+		if (priv->irq && !mnp)
  			mt7530_free_mdio_irq(priv);
  	}
  
+out:
+	of_node_put(mnp);
  	return ret;
  }
  

Arınç