Re: [PATCH] ARM: dts: BCM5301X: Add DT for Asus RT-AC88U

[Florian Fainelli <f.fainelli@gmail.com>]

On 9/24/21 2:02 PM, Arınç ÜNAL wrote:
>> 0x200 is not the address of the Realtek switch on the MDIO bus, 0x200 is
>> the offset with mdio mux that needs to be toggled (bit 9). You still
>> need to provide the Ethernet switch's address on the MDIO bus which
>> appears to be 0.
> 
> Oh, we flip the 9th bit. 2 to the power of 9 = 0x200. Got it!
> 
> I tried 0 and 29 as the PHY ID. I'd assume the DSA realtek-smi driver
> would start probing the switch, however, nothing happens. Full log in
> attachments.
> 
> [    2.026772] bcm_iproc 18029200.spi: using bspi-mspi mode
> [    2.033467] libphy: Fixed MDIO Bus: probed
> [    2.038123] libphy: iProc MDIO bus: probed
> [    2.042331] iproc-mdio 18003000.mdio: Broadcom iProc MDIO bus registered
> [    2.049823] libphy: mdio_mux: probed
> [    2.054206] libphy: mdio_mux: probed
> [    2.058713] b53-srab-switch 18007000.ethernet-switch: found switch:
> BCM53012, rev 0
> [    2.066671] bgmac_bcma: Broadcom 47xx GBit MAC driver loaded
> 
> Quoting Documentation/devicetree/bindings/net/dsa/realtek-smi.txt for
> further reference.
> 
>> Realtek SMI-based Switches
>> ==========================
>>
>> The SMI "Simple Management Interface" is a two-wire protocol using
>> bit-banged GPIO that while it reuses the MDIO lines MCK and MDIO does
>> not use the MDIO protocol. This binding defines how to specify the
>> SMI-based Realtek devices.

Ah this is the key here, using the MDIO controller won't work sorry
about misleading you. I suppose you will have to go back to the previous
Device Tree representation you had, but change the dsa,member property
and then you should be in business baring additional bugs/features.
-- 
Florian