linux-kernel - Re: [PATCH net-next 07/15] net: dsa: mt7530: do not run mt7530_setup

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Message-ID: <a2826485-70a6-4ba7-89e1-59e68e622901@arinc9.com>
Date:   Sat, 2 Dec 2023 11:45:42 +0300
From:   Arınç ÜNAL <arinc.unal@...nc9.com>
To:     Simon Horman <horms@...nel.org>
Cc:     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>,
        Vladimir Oltean <olteanv@...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>,
        Russell King <linux@...linux.org.uk>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Bartel Eerdekens <bartel.eerdekens@...stell8.be>,
        mithat.guner@...ont.com, erkin.bozoglu@...ont.com
Subject: Re: [PATCH net-next 07/15] net: dsa: mt7530: do not run
 mt7530_setup_port5() if port 5 is disabled

Hi Simon.

On 21.11.2023 21:53, Simon Horman wrote:
> On Sat, Nov 18, 2023 at 03:31:57PM +0300, Arınç ÜNAL wrote:
>> There's no need to run all the code on mt7530_setup_port5() if port 5 is
>> disabled. The only case for calling mt7530_setup_port5() from
>> mt7530_setup() is when PHY muxing is enabled. That is because port 5 is not
>> defined as a port on the devicetree, therefore, it cannot be controlled by
>> phylink.
>>
>> Because of this, run mt7530_setup_port5() if priv->p5_intf_sel is
>> P5_INTF_SEL_PHY_P0 or P5_INTF_SEL_PHY_P4. Remove the P5_DISABLED case from
>> mt7530_setup_port5().
>>
>> Stop initialising the interface variable as the remaining cases will always
>> call mt7530_setup_port5() with it initialised.
>>
>> Signed-off-by: Arınç ÜNAL <arinc.unal@...nc9.com>
>> Reviewed-by: Vladimir Oltean <olteanv@...il.com>
>> ---
>>   drivers/net/dsa/mt7530.c | 9 +++------
>>   1 file changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
>> index fc87ec817672..1aab4c3f28b0 100644
>> --- a/drivers/net/dsa/mt7530.c
>> +++ b/drivers/net/dsa/mt7530.c
>> @@ -942,9 +942,6 @@ static void mt7530_setup_port5(struct dsa_switch *ds, phy_interface_t interface)
>>   		/* MT7530_P5_MODE_GMAC: P5 -> External phy or 2nd GMAC */
>>   		val &= ~MHWTRAP_P5_DIS;
>>   		break;
>> -	case P5_DISABLED:
>> -		interface = PHY_INTERFACE_MODE_NA;
>> -		break;
>>   	default:
>>   		dev_err(ds->dev, "Unsupported p5_intf_sel %d\n",
>>   			priv->p5_intf_sel);
>> @@ -2313,8 +2310,6 @@ mt7530_setup(struct dsa_switch *ds)
>>   		 * Set priv->p5_intf_sel to the appropriate value if PHY muxing
>>   		 * is detected.
>>   		 */
>> -		interface = PHY_INTERFACE_MODE_NA;
>> -
>>   		for_each_child_of_node(dn, mac_np) {
>>   			if (!of_device_is_compatible(mac_np,
>>   						     "mediatek,eth-mac"))
>> @@ -2346,7 +2341,9 @@ mt7530_setup(struct dsa_switch *ds)
>>   			break;
>>   		}
>>   
>> -		mt7530_setup_port5(ds, interface);
>> +		if (priv->p5_intf_sel == P5_INTF_SEL_PHY_P0 ||
>> +		    priv->p5_intf_sel == P5_INTF_SEL_PHY_P4)
>> +			mt7530_setup_port5(ds, interface);
> 
> Hi Arınç,
> 
> It appears that interface is now uninitialised here.
> 
> Flagged by Smatch.

I'm not sure why it doesn't catch that for mt7530_setup_port5() to run
here, priv->p5_intf_sel must be either P5_INTF_SEL_PHY_P0 or
P5_INTF_SEL_PHY_P4. And for that to happen, the interface variable will be
initialised.

for_each_child_of_node(dn, mac_np) {
	if (!of_device_is_compatible(mac_np,
				     "mediatek,eth-mac"))
		continue;

	ret = of_property_read_u32(mac_np, "reg", &id);
	if (ret < 0 || id != 1)
		continue;

	phy_node = of_parse_phandle(mac_np, "phy-handle", 0);
	if (!phy_node)
		continue;

	if (phy_node->parent == priv->dev->of_node->parent) {
		ret = of_get_phy_mode(mac_np, &interface);
		if (ret && ret != -ENODEV) {
			of_node_put(mac_np);
			of_node_put(phy_node);
			return ret;
		}
		id = of_mdio_parse_addr(ds->dev, phy_node);
		if (id == 0)
			priv->p5_intf_sel = P5_INTF_SEL_PHY_P0;
		if (id == 4)
			priv->p5_intf_sel = P5_INTF_SEL_PHY_P4;
	}
	of_node_put(mac_np);
	of_node_put(phy_node);
	break;
}

if (priv->p5_intf_sel == P5_INTF_SEL_PHY_P0 ||
     priv->p5_intf_sel == P5_INTF_SEL_PHY_P4)
	mt7530_setup_port5(ds, interface);

Arınç