On Tue, Nov 06, 2018 at 11:48:30AM +0000, Florinel Iordache wrote:
> Device Tree Bindings for DPAA backplane available on Layerscape
> communications processors.
>
> Signed-off-by: Florinel Iordache <florinel.iordache@xxxxxxx>
> ---
> .../devicetree/bindings/net/dpaa-backplane.txt | 105 +++++++++++++++++++++
> 1 file changed, 105 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/net/dpaa-backplane.txt
>
> diff --git a/Documentation/devicetree/bindings/net/dpaa-backplane.txt b/Documentation/devicetree/bindings/net/dpaa-backplane.txt
> new file mode 100644
> index 0000000..f147c84
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/dpaa-backplane.txt
> @@ -0,0 +1,105 @@
> +=============================================================================
> +DPAA Backplane Device Bindings
> +
> +CONTENTS
> + - SerDes Node
> + - PCS Phy Node
> +
> +=============================================================================
> +SerDes Node
> +
> +DESCRIPTION
> +
> +SerDes (Serializer/Deserializer) HW peripheral
> +
Hi Florinel
It is normal to indicate which properties are required, and which are
optional using the section headers. There is a defacto standard for
the format of a device tree binding, and this text does not follow it.
> +PROPERTIES
> +
> +- compatible
> + Usage: required
> + Value type: <stringlist>
> + Definition: Specifies the type of SerDes.
> + Must include the prefix "fsl,serdes"
> + SerDes can be of different types:
> + - 10G SerDes must be specified as: "fsl,serdes-10g"
> + - 28G SerDes must be specified as: "fsl,serdes-28g"
Does a different driver get loaded depending on the compatible? I'm
just wondering if there should be one compatible string, and a speed
property.
> +
> +- reg
> + Usage: required
> + Value type: <prop-encoded-array>
> + Definition: Specifies the offset of the SerDes configuration registers
> +
> +- little-endian
> + Usage: optional
> + Value type: <Boolean>
> + Definition: Specifies endianness access to SerDes registers.
> + If omitted, big-endian will be used
> + See common-properties.txt for complete definition
> +
> +EXAMPLE
> +
> +Example of 10G SerDes node:
> +
> +serdes1: serdes@1ea0000 {
> + compatible = "fsl,serdes-10g";
> + reg = <0x0 0x1ea0000 0 0x00002000>;
> + little-endian;
> +};
> +
> +=============================================================================
> +PCS Phy Node
> +
> +DESCRIPTION
> +
> +PCS Phy (Physical Coding Sublayer / Physical layer) node
> +
> +PROPERTIES
> +
> +- compatible
> + Usage: required
This is normally optional, and defaults to c22 if not present.
> + Value type: <stringlist>
> + Definition: A standard property. Specifies the IEEE 802.3 Clause
> + Different IEEE 802.3 Clauses can be specified:
> + - Clause 22 must be specified as: "ethernet-phy-ieee802.3-c22"
> + - Clause 45 must be specified as: "ethernet-phy-ieee802.3-c45"
> + For complete definition see:
> + Documentation/devicetree/bindings/net/phy.txt
> +
> +- reg
> + Usage: required
> + Value type: <prop-encoded-array>
> + Definition: A standard property.
> + Specifies the offset of the PCS Phy configuration registers
> + For complete definition see:
> + Documentation/devicetree/bindings/net/phy.txt
Rather than state what is already in phy.txt, just say that the
following additional properties can be used:
> +
> +- backplane-mode
> + Usage: required
So your PHYs can only be used in backplane-mode? Base-T is never
supported?
> + Value type: <stringlist>
> + Definition: Specifies the speed and type of the protocol used
> + Different speeds and backplane protocol types can be used:
> + - 10GBase-KR must be specified as: "10gbase-kr"
> + - 40GBase-KR must be specified as: "40gbase-kr"
I don't see why this is needed. The PHY driver should know what speeds
the PHY supports. You might want to make use of the standard max-speed
property to prevent it doing a high speed, because of layout issues,
etc.
> +
> +- fsl,lane-handle
> + Usage: required
> + Value type: <phandle>
> + Definition: Specifies the reference to a node representing the SerDes
> + device
> +
> +- fsl,lane-reg
> + Usage: required
> + Value type: <prop-encoded-array>
> + Definition: Specifies the offsets of the SerDes lanes configuration
> + registers
No other PHY driver we have needs such properties. Why are these
needed?
It is also a bit ununsed to post a binding without the code. Maybe the
code for these two drivers will help me understand.
Thanks
Andrew
