Subject: Re: [BUG] Unable to handle kernel NULL pointer dereference in phy_support_asym_pause

From: Andrew Lunn <[email-masked]>
Date: Wed, 25 Sep 2019 02:44:37 +0200

On Tue, Sep 24, 2019 at 03:10:44PM +0200, Michal Vokáč wrote:
> On 24. 09. 19 14:31, Andrew Lunn wrote:
> I added the printk and the above fix and can confirm that it is the CPU
> port and the phy is NULL pointer:
> 
> [    6.976366] qca8k 2188000.ethernet-1:0a: Using legacy PHYLIB callbacks. Please migrate to PHYLINK!
> [    6.992021] qca8k 2188000.ethernet-1:0a: port: 0, phy: 0
> [    7.001323] qca8k 2188000.ethernet-1:0a eth2 (uninitialized): PHY [2188000.ethernet-1:01] driver [Generic PHY]
> [    7.014221] qca8k 2188000.ethernet-1:0a eth2 (uninitialized): phy: setting supported 00,00000000,000062ef advertising 00,00000000,000062ef
> [    7.030598] qca8k 2188000.ethernet-1:0a eth1 (uninitialized): PHY [2188000.ethernet-1:02] driver [Generic PHY]
> [    7.043500] qca8k 2188000.ethernet-1:0a eth1 (uninitialized): phy: setting supported 00,00000000,000062ef advertising 00,00000000,000062ef
> [    7.063335] DSA: tree 0 setup
> 
> Now the device boots but there is a problem with the CPU port configuration:

Hi Michal

Thanks for testing. I will post a different fix very soon.

> root@hydraco:~# ifconfig eth0 up
> [  255.256047] Generic PHY fixed-0:00: attached PHY driver [Generic PHY] (mii_bus:phy_addr=fixed-0:00, irq=POLL)
> [  255.272449] fec 2188000.ethernet eth0: Link is Up - 1Gbps/Full - flow control off
> [  255.286539] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
> root@hydraco:~# ifconfig eth1 up
> [  268.350078] qca8k 2188000.ethernet-1:0a: port: 3, phy: -393143296
> [  268.364442] qca8k 2188000.ethernet-1:0a eth1: configuring for phy/ link mode
> [  268.375400] qca8k 2188000.ethernet-1:0a eth1: phylink_mac_config: mode=phy//Unknown/Unknown adv=00,00000000,000062ef pause=10 link=0 an=1
> [  268.393901] qca8k 2188000.ethernet-1:0a eth1: phy link up /1Gbps/Full
> [  268.404849] qca8k 2188000.ethernet-1:0a eth1: phylink_mac_config: mode=phy//1Gbps/Full adv=00,00000000,00000000 pause=0e link=1 an=0
> [  268.420740] qca8k 2188000.ethernet-1:0a eth1: Link is Up - 1Gbps/Full - flow control rx/tx
> [  268.432995] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
> root@hydraco:~# udhcpc -i eth1
> udhcpc (v1.23.2) started
> Sending discover...
> Sending discover...
> Sending discover...

This i think is something different. What looks odd is
imx6dl-yapp4-common.dtsi

&fec {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_enet>;
        phy-mode = "rgmii-id";
        phy-reset-gpios = <&gpio1 25 GPIO_ACTIVE_LOW>;
        phy-reset-duration = <20>;
        phy-supply = <&sw2_reg>;
        phy-handle = <&ethphy0>;
        status = "okay";

	mdio {

               switch@10 {
                        compatible = "qca,qca8334";
                        reg = <10>;

                        switch_ports: ports {
                                #address-cells = <1>;
                                #size-cells = <0>;

                                ethphy0: port@0 {
                                        reg = <0>;
                                        label = "cpu";
                                        phy-mode = "rgmii-id";
                                        ethernet = <&fec>;

Both the FEC and the CPU port are set to use rgmii-id". So we are
getting double delays.

Try changing one of these to plain rgmii.

    Andrew