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SubjectRe: [PATCH 07/10] ARM: dts: sun7i: cubietruck: Enable the GMAC
On Tue, Dec 10, 2013 at 1:48 AM, Florian Fainelli <> wrote:
> 2013/12/8 Chen-Yu Tsai <>:
>> Florian, Giuseppe:
>> On Sat, Dec 7, 2013 at 9:57 AM, Florian Fainelli <> wrote:
>>> 2013/12/6 Chen-Yu Tsai <>:
>>>> On Sat, Dec 7, 2013 at 5:09 AM, Florian Fainelli <> wrote:
>>>>> 2013/12/6 Chen-Yu Tsai <>:
>>>>>> The CubieTruck uses the GMAC with an RGMII phy.
>>>>>> Signed-off-by: Chen-Yu Tsai <>
>>>>>> ---
>>>>>> arch/arm/boot/dts/sun7i-a20-cubietruck.dts | 8 ++++++++
>>>>>> 1 file changed, 8 insertions(+)
>>>>>> diff --git a/arch/arm/boot/dts/sun7i-a20-cubietruck.dts b/arch/arm/boot/dts/sun7i-a20-cubietruck.dts
>>>>>> index 8a1009d..af212a2 100644
>>>>>> --- a/arch/arm/boot/dts/sun7i-a20-cubietruck.dts
>>>>>> +++ b/arch/arm/boot/dts/sun7i-a20-cubietruck.dts
>>>>>> @@ -33,6 +33,14 @@
>>>>>> pinctrl-0 = <&uart0_pins_a>;
>>>>>> status = "okay";
>>>>>> };
>>>>>> +
>>>>>> + gmac: ethernet@01c50000 {
>>>>>> + pinctrl-names = "default";
>>>>>> + pinctrl-0 = <&gmac_pins_rgmii>;
>>>>>> + snps,phy-addr = <1>;
>>>>> What is this snps,phy-addr property? Why is not a standard device tree
>>>>> node for an Ethernet PHY node used?
>>>> This property is implemented by stmmac and documented in the DT
>>>> bindings. stmmac has not been updated to use Ethernet PHY nodes.
>>> This driver property should be removed and deprecated since there is
>>> an ePAPR standardized Ethernet PHY node. What I am worried here is the
>>> loss of information, the standard Ethernet DT node allows to specify
>>> much more information (clause, maximum speed, compatible string
>>> etc...).
>> Giuseppe, any thoughts on this?
>>>> Removing this property will not affect the function of the driver.
>>>> The driver probes its MDIO bus and selects the lowest available
>>>> address if not specified.
>>> So if this is just giving the driver a hint on where to probe for a
>>> PHY on the MDIO bus, then let's drop it and use the standard DT node
>>> no?
>> Sure. I will remove it from the DT.
>> The stmmac driver does not have a seperate MDIO bus driver, nor
>> does it support Ethernet PHY node bindings. So I will not add
>> a phy node at this moment.
> This will create needless churn in the DT if you do not do it now,
> worse actually, we switch from a DT which specifically described
> Ethernet PHY nodes properly to a version where it does, to ultimately
> a newer version which does.
> Considering that the absence of a "snps,phy-addr" property will still
> result in the MDIO bus to be probed, keeping the existing Ethernet PHY
> nodes, referencing them correclty with a "phy-handle" property, but
> having no explicit support for these in the driver will not result in
> a functional change, and will reduce the DT churn. Also, you could
> still sneak a patch in this patchset which parses the standard
> EThernet PHY node binding.

I see. Adding the PHY node should be no trouble at all.
Is there a requirement for a seperate mdio bus in the DT?
I do not see it in the ePAPR. The stmmac mdio is not a seperate
driver, as is for most network controllers I presume.
Would attaching the PHY nodes directly under the ethernet controller

We can then introduce PHY node support to the driver and
remove the "snps,phy-addr" property at the same time.


>>>>>> + phy-mode = "rgmii";
>>>>> Especially since you use the relatively standard "phy-mode" property here?
>>>> Used as specified in stmmac DT bindings.
>>> That one is kind of okay because of_get_phy_mode() knows about it,
>>> even though ePAPR states this should be "phy-connection-type", so I am
>>> okay with keeping that one because current practice and helpers are
>>> here.
>> It seems all ARM DTs currently use "phy-mode".
> Which is why I said "is kind of okay", but this is not what the
> standard came up with, ARM is not exactly the best DT-citizen out
> there as people are prone to making up new properties when the
> standard already defines some, anyway....
> --
> Florian

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