Subject: Re: SoCFPGA ethernet broken

From: Florian Fainelli <[email-masked]>
Date: Thu, 15 Oct 2015 13:25:59 -0700

On 15/10/15 12:59, Dinh Nguyen wrote:
> On 10/15/2015 03:03 PM, Florian Fainelli wrote:
>> On 15/10/15 12:09, Dinh Nguyen wrote:
>>> Hi,
>>>
>>> commit "8b63ec1837fa phylib: Make PHYs children of their MDIO bus, not
>>> the bus' parent." seems to have broken ethernet support for the SoCFPGA
>>> platform which is using the stmmac ethernet driver.
>>
>> It is not clear to me how this relates to what you are seeing yet.
>>
>>>
>>> It appears that during DHCP, it cannot get an IP address. This only
>>> happens if ethernet was not used by the bootloader to tftp an kernel
>>> image. If I use the bootloader to tftp an image then ethernet is working
>>> fine. So I think the PHY is not getting enabled properly.
>>>
>>> If I revert this patch, then ethernet is back to working on the platform.
>>
>> Is the Device Tree source for this platform available somewhere to look at?
>>
> 
> Yes, I'm using the DTS that is in the mainline:
> 
> arch/arm/boot/dts/socfpga.dtsi
> arch/arm/boot/dts/socfpga_cyclone5.dtsi
> arch/arm/boot/dts/socfpga_cyclone5_socdk.dts

There are no PHY devices in any of these DTS files, instead there is the
non-standard "phy-addr" property which is set to 0xffffffff supposedly
to indicate that the MDIO bus should be scanned. This is likely part of
your problem. The stmmac driver seems to be looking for "snps,phy-addr"
and not "phy-addr", so I am not even clear how this is supposed to work,
and the driver mentions this custom property is deprecated anyway.

The core problem is in
drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c::stmmac_mdio_register
which manually detects the PHY, that is mostly fine, except that it does
not really seem to work here for a reason that is still unclear to me.

Your Ethernet PHYs need to be declared in Device Tree, see
Documentation/devicetree/bindings/net/phy.txt

but aside from that, what should be the PHY driver used by our platform?
ID 00221611 does not seem to be claimed by any known PHY driver, so that
leave us with the Generic PHY driver I guess?

Do you have specific PHY fixups required for this platform?
-- 
Florian