[PATCH v2 1/7] net: dt-bindings: add RGMII TX delay configuration to meson8b-dwmac
Rob Herring
robh at kernel.org
Wed Nov 30 13:44:29 PST 2016
On Fri, Nov 25, 2016 at 02:01:50PM +0100, Martin Blumenstingl wrote:
> This allows configuring the RGMII TX clock delay. The RGMII clock is
> generated by underlying hardware of the the Meson 8b / GXBB DWMAC glue.
> The configuration depends on the actual hardware (no delay may be
> needed due to the design of the actual circuit, the PHY might add this
> delay, etc.).
>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl at googlemail.com>
> ---
> Documentation/devicetree/bindings/net/meson-dwmac.txt | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/net/meson-dwmac.txt b/Documentation/devicetree/bindings/net/meson-dwmac.txt
> index 89e62dd..f8bc540 100644
> --- a/Documentation/devicetree/bindings/net/meson-dwmac.txt
> +++ b/Documentation/devicetree/bindings/net/meson-dwmac.txt
> @@ -25,6 +25,20 @@ Required properties on Meson8b and newer:
> - "clkin0" - first parent clock of the internal mux
> - "clkin1" - second parent clock of the internal mux
>
> +Optional properties on Meson8b and newer:
> +- amlogic,tx-delay-ns: The internal RGMII TX clock delay (provided
> + by this driver) in nanoseconds. Allowed values
> + are: 0ns, 2ns, 4ns, 6ns.
> + This must be configured when the phy-mode is
> + "rgmii" (typically a value of 2ns is used in
> + this case).
> + When phy-mode is set to "rgmii-id" or
> + "rgmii-txid" the TX clock delay is already
> + provided by the PHY. In that case this
> + property should be set to 0ns (which disables
> + the TX clock delay in the MAC to prevent the
> + clock from going off because both PHY and MAC
> + are adding a delay).
What's the default? Why can't no property mean 0ns delay?
>
> Example for Meson6:
>
> --
> 2.10.2
>
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