[PATCH net-next] net: dsa: mt753x: fix pcs conversion regression

[Florian Fainelli]

On 4/25/22 14:28, Russell King (Oracle) wrote:
> Daniel Golle reports that the conversion of mt753x to phylink PCS caused
> an oops as below.
> 
> The problem is with the placement of the PCS initialisation, which
> occurs after mt7531_setup() has been called. However, burited in this
> function is a call to setup the CPU port, which requires the PCS
> structure to be already setup.
> 
> Fix this by changing the initialisation order.
> 
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
> Mem abort info:
>    ESR = 0x96000005
>    EC = 0x25: DABT (current EL), IL = 32 bits
>    SET = 0, FnV = 0
>    EA = 0, S1PTW = 0
>    FSC = 0x05: level 1 translation fault
> Data abort info:
>    ISV = 0, ISS = 0x00000005
>    CM = 0, WnR = 0
> user pgtable: 4k pages, 39-bit VAs, pgdp=0000000046057000
> [0000000000000020] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
> Internal error: Oops: 96000005 [#1] SMP
> Modules linked in:
> CPU: 0 PID: 32 Comm: kworker/u4:1 Tainted: G S 5.18.0-rc3-next-20220422+ #0
> Hardware name: Bananapi BPI-R64 (DT)
> Workqueue: events_unbound deferred_probe_work_func
> pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : mt7531_cpu_port_config+0xcc/0x1b0
> lr : mt7531_cpu_port_config+0xc0/0x1b0
> sp : ffffffc008d5b980
> x29: ffffffc008d5b990 x28: ffffff80060562c8 x27: 00000000f805633b
> x26: ffffff80001a8880 x25: 00000000000009c4 x24: 0000000000000016
> x23: ffffff8005eb6470 x22: 0000000000003600 x21: ffffff8006948080
> x20: 0000000000000000 x19: 0000000000000006 x18: 0000000000000000
> x17: 0000000000000001 x16: 0000000000000001 x15: 02963607fcee069e
> x14: 0000000000000000 x13: 0000000000000030 x12: 0101010101010101
> x11: ffffffc037302000 x10: 0000000000000870 x9 : ffffffc008d5b800
> x8 : ffffff800028f950 x7 : 0000000000000001 x6 : 00000000662b3000
> x5 : 00000000000002f0 x4 : 0000000000000000 x3 : ffffff800028f080
> x2 : 0000000000000000 x1 : ffffff800028f080 x0 : 0000000000000000
> Call trace:
>   mt7531_cpu_port_config+0xcc/0x1b0
>   mt753x_cpu_port_enable+0x24/0x1f0
>   mt7531_setup+0x49c/0x5c0
>   mt753x_setup+0x20/0x31c
>   dsa_register_switch+0x8bc/0x1020
>   mt7530_probe+0x118/0x200
>   mdio_probe+0x30/0x64
>   really_probe.part.0+0x98/0x280
>   __driver_probe_device+0x94/0x140
>   driver_probe_device+0x40/0x114
>   __device_attach_driver+0xb0/0x10c
>   bus_for_each_drv+0x64/0xa0
>   __device_attach+0xa8/0x16c
>   device_initial_probe+0x10/0x20
>   bus_probe_device+0x94/0x9c
>   deferred_probe_work_func+0x80/0xb4
>   process_one_work+0x200/0x3a0
>   worker_thread+0x260/0x4c0
>   kthread+0xd4/0xe0
>   ret_from_fork+0x10/0x20
> Code: 9409e911 937b7e60 8b0002a0 f9405800 (f9401005)
> ---[ end trace 0000000000000000 ]---
> 
> Reported-by: Daniel Golle <daniel at makrotopia.org>
> Tested-by: Daniel Golle <daniel at makrotopia.org>
> Fixes: cbd1f243bc41 ("net: dsa: mt7530: partially convert to phylink_pcs")
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>

Reviewed-by: Florian Fainelli <f.fainelli at gmail.com>
-- 
Florian