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SubjectRe: [PATCH v9 05/15] dt-bindings: connector: Add property to set initial current cap for FRS
On Mon, Sep 28, 2020 at 07:39:54PM -0700, Badhri Jagan Sridharan wrote:
> This change adds frs-typec-current which allows setting the initial current
> capability of the new source when vSafe5V is applied during PD3.0
> sink Fast Role Swap.

Shouldn't you Cc the person you copied this from?


> Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
> ---
> Changes since v1:
> - Changing patch version to v6 to fix version number confusion.
>
> Changes since v6:
> - Removed the redundant usb-connector.txt that I created by mistake.
> - Moved to yaml.
>
> Changes since v7:
> - Rebase
>
> Changes since v8:
> - Redefine new-source-frs-typec-current as string enums to address
> Rob Herring's comment.
> ---
> .../bindings/connector/usb-connector.yaml | 26 +++++++++++++++++++
> include/dt-bindings/usb/pd.h | 10 +++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/connector/usb-connector.yaml b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> index 9bd52e63c935..0b8cd08a8678 100644
> --- a/Documentation/devicetree/bindings/connector/usb-connector.yaml
> +++ b/Documentation/devicetree/bindings/connector/usb-connector.yaml
> @@ -142,6 +142,32 @@ properties:
> required:
> - port@0
>
> + new-source-frs-typec-current:
> + description: Initial current capability of the new source when vSafe5V
> + is applied during PD3.0 Fast Role Swap. "Table 6-14 Fixed Supply PDO - Sink"
> + of "USB Power Delivery Specification Revision 3.0, Version 1.2" provides the
> + different power levels and "6.4.1.3.1.6 Fast Role Swap USB Type-C Current"
> + provides a detailed description of the field. The sink PDO from current source
> + reflects the current source's(i.e. transmitter of the FRS signal) power
> + requirement during fr swap. The current sink (i.e. receiver of the FRS signal),
> + a.k.a new source, should check if it will be able to satisfy the current source's,
> + new sink's, requirement during frswap before enabling the frs signal reception.
> + This property refers to maximum current capability that the current sink can
> + satisfy. During FRS, VBUS voltage is at 5V, as the partners are in implicit
> + contract, hence, the power level is only a function of the current capability.
> + "not-supported" implies sink to source fast role swap not supported.
> + "default" refers to default USB power level as described by
> + "Table 6-14 Fixed Supply PDO - Sink".
> + "1.5A" refers to 1.5A@5V.
> + "3.0A" refers to 3.0A@5V.


> +
> + $ref: /schemas/types.yaml#/definitions/string
> + enum:
> + - not-supported
> + - default
> + - 1.5A
> + - 3.0A

What happens if the property is not present?

I'm not crazy about mixing strings and what could be a number.

> +
> required:
> - compatible
>
> diff --git a/include/dt-bindings/usb/pd.h b/include/dt-bindings/usb/pd.h
> index 985f2bbd4d24..db1ad4532197 100644
> --- a/include/dt-bindings/usb/pd.h
> +++ b/include/dt-bindings/usb/pd.h
> @@ -35,6 +35,16 @@
>
> #define VSAFE5V 5000 /* mv units */
>
> +/*
> + * Based on "Table 6-14 Fixed Supply PDO - Sink" of "USB Power Delivery Specification Revision 3.0,
> + * Version 1.2"
> + * Initial current capability of the new source when vSafe5V is applied.
> + */
> +#define FRS_NOT_SUPPORTED 0
> +#define FRS_DEFAULT_POWER 1
> +#define FRS_5V_1P5A 2
> +#define FRS_5V_3A 3

Why are these in a DT header, but not used by the binding? Though
perhaps they should be. Are these numbers from the spec or made up?

> +
> #define PDO_BATT_MAX_VOLT_SHIFT 20 /* 50mV units */
> #define PDO_BATT_MIN_VOLT_SHIFT 10 /* 50mV units */
> #define PDO_BATT_MAX_PWR_SHIFT 0 /* 250mW units */
> --
> 2.28.0.709.gb0816b6eb0-goog
>

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