[meta-xilinx] macb.c and DT: detect/scan PHY address for a single mdio

[Mike Looijmans]

"0" is not a valid address for a PHY, it's the "broadcast" address on the MDIO 
bus. You should make your hardware designer who selected it hurt somewhere 
painful.

Having said that, address 0 usally happens to work if there's only one PHY on 
that bus, since it will be the only one responding to that broadcast.

Change reg = <0x3> to reg = <0x0> in the devicetree. You can optionally change 
the descriptions as well, but it's the "reg" that really matters. This might 
work on the board with address "3" because that will also respond to the 
broadcast address 0.



On 18-07-18 03:12, Oleg K Dzhimiev wrote:
> Hi,
> 
> How do I keep the device tree compatible across the board revisions if phy 
> addrs are different?
> We got a new board revision with a different phy reg, where old rev reg == 
> 0x3, new rev reg == 0x0.
> 
> Here's the DT:
> 
>     ps7_ethernet_0: ps7-ethernet at e000b000 {
>     local-mac-address = [00 0e 64 10 00 00];
>     phy-handle = <&phy3>;
>     phy-mode = "rgmii-id";
>     mdio {
>     #address-cells = <1>;
>     #size-cells = <0>;
>     phy3: phy at 3 {
>                                              /* Atheros 8035 */
>                                              compatible =
>     "ethernet-phy-id004d.d072";
>     /* compatible = "ethernet-phy-ieee802.3-c22";*/
>     device_type = "ethernet-phy";
>     reg = <0x3>;
>     };
>     };
>     };
> 
> 
> So far, with the old revision (addr==0x3) I have tried to remove 'reg' hoping 
> it would do some sort of scanning but the macb driver (macb_mii_probe) 
> registers 32 phy structs then picks the first one (addr==0) and timeouts 
> trying to reset it.
> 
> Thanks,
> 
> Oleg Dzhimiev
> Electronics Engineer
> phone: +1 801 783 5555 x124
> Elphel, Inc.
> 
>