Re: [RFC PATCH 2/3] dt-bindings: net: phy: Add support for AT803X

[Florian Fainelli]

On 10/30/19 3:42 PM, Michael Walle wrote:
> Document the Atheros AR803x PHY bindings.
> 
> Signed-off-by: Michael Walle <michael@xxxxxxxx>
> ---
>  .../bindings/net/atheros,at803x.yaml          | 58 +++++++++++++++++++
>  include/dt-bindings/net/atheros-at803x.h      | 13 +++++
>  2 files changed, 71 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/atheros,at803x.yaml
>  create mode 100644 include/dt-bindings/net/atheros-at803x.h
> 
> diff --git a/Documentation/devicetree/bindings/net/atheros,at803x.yaml b/Documentation/devicetree/bindings/net/atheros,at803x.yaml
> new file mode 100644
> index 000000000000..60500fd90fd8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/atheros,at803x.yaml
> @@ -0,0 +1,58 @@
> +# SPDX-License-Identifier: GPL-2.0+
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/net/atheros,at803x.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Atheros AR803x PHY
> +
> +maintainers:
> +  - TBD
> +
> +description: |
> +  Bindings for Atheros AR803x PHYs
> +
> +allOf:
> +  - $ref: ethernet-phy.yaml#
> +
> +properties:
> +  atheros,clk-out-frequency:
> +    description: Clock output frequency in Hertz.
> +    enum: [ 25000000, 50000000, 62500000, 125000000 ]
> +
> +  atheros,clk-out-strength:
> +    description: Clock output driver strength.
> +    enum: [ 0, 1, 2 ]
> +
> +  atheros,keep-pll-enabled:
> +    description: |
> +      If set, keep the PLL enabled even if there is no link. Useful if you
> +      want to use the clock output without an ethernet link.

This is more of a policy than a hardware description. Implementing this
has a PHY tunable, possibly as a form of auto-power down

> +    type: boolean
> +
> +  atheros,rgmii-io-1v8:
> +    description: |
> +      The PHY supports RGMII I/O voltages of 2.5V, 1.8V and 1.5V. By default,
> +      the PHY uses a voltage of 1.5V. If this is set, the voltage will changed
> +      to 1.8V.

will be changed?

This looks like a possibly dangerous configuration as it really can lead
to some good damage happening on the pins if there is an incompatible
voltage on the MAC and PHY side... of course, you have no way to tell
ahead of time other than by looking at the board schematics, lovely.

Does the PHY come up in some sort of super isolatation mode by default
at least?
-- 
Florian