Re: [RFC PATCH 2/9] dt-bindings: memory-controller: Add apple,mcc binding

From: Krzysztof Kozlowski
Date: Tue Oct 12 2021 - 04:48:21 EST


On 11/10/2021 18:57, Hector Martin wrote:
> This device represents the memory controller in Apple SoCs, and is
> chiefly in charge of adjusting performance characteristics according to
> system demand.
>
> Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
> ---
> .../memory-controllers/apple,mcc.yaml | 80 +++++++++++++++++++
> .../opp/apple,mcc-operating-points.yaml | 62 ++++++++++++++
> 2 files changed, 142 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/memory-controllers/apple,mcc.yaml
> create mode 100644 Documentation/devicetree/bindings/opp/apple,mcc-operating-points.yaml
>
> diff --git a/Documentation/devicetree/bindings/memory-controllers/apple,mcc.yaml b/Documentation/devicetree/bindings/memory-controllers/apple,mcc.yaml
> new file mode 100644
> index 000000000000..0774f10e65ed
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/apple,mcc.yaml
> @@ -0,0 +1,80 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/memory-controllers/apple,mcc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SoC MCC memory controller performance controls
> +
> +maintainers:
> + - Hector Martin <marcan@xxxxxxxxx>
> +
> +description: |
> + Apple SoCs contain a multichannel memory controller that can have its
> + configuration changed to adjust to changing performance requirements from
> + the rest of the SoC. This node represents the controller and provides a
> + power domain provider that downstream devices can use to adjust the memory
> + controller performance level.
> +
> +properties:
> + compatible:
> + items:
> + - enum:
> + - apple,t8103-mcc
> + - const: apple,mcc
> +
> + reg:
> + maxItems: 1
> +
> + "#power-domain-cells":
> + const: 0
> +
> + operating-points-v2:
> + $ref: /schemas/types.yaml#/definitions/phandle-array
> + description:
> + A reference to the OPP table describing the memory controller performance
> + levels. Each OPP node should contain an `apple,memory-perf-config`
> + property that contains the configuration values for that performance
> + level.
> +
> + apple,num-channels:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + The number of memory channels in use.
> +
> +required:
> + - compatible
> + - reg
> + - "#power-domain-cells"
> + - operating-points-v2
> + - apple,num-channels
> +
> +additionalProperties: false
> +
> +examples:
> + # See clock/apple,cluster-clock.yaml for an example of downstream usage.
> + - |
> + mcc_opp: opp-table-2 {
> + compatible = "operating-points-v2";

apple,mcc-operating-points?

> +
> + mcc_lowperf: opp0 {
> + opp-level = <0>;
> + apple,memory-perf-config = <0x813057f 0x1800180>;
> + };
> + mcc_highperf: opp1 {
> + opp-level = <1>;
> + apple,memory-perf-config = <0x133 0x55555340>;
> + };
> + };
> + soc {
> + #address-cells = <2>;
> + #size-cells = <2>;
> +
> + mcc: memory-controller@200200000 {
> + compatible = "apple,t8103-mcc", "apple,mcc";
> + #power-domain-cells = <0>;
> + reg = <0x2 0x200000 0x0 0x200000>;
> + operating-points-v2 = <&mcc_opp>;
> + apple,num-channels = <8>;
> + };
> + };
> diff --git a/Documentation/devicetree/bindings/opp/apple,mcc-operating-points.yaml b/Documentation/devicetree/bindings/opp/apple,mcc-operating-points.yaml
> new file mode 100644
> index 000000000000..babf27841bb7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/opp/apple,mcc-operating-points.yaml
> @@ -0,0 +1,62 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/opp/apple,mcc-operating-points.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SoC memory controller OPP bindings
> +
> +maintainers:
> + - Hector Martin <marcan@xxxxxxxxx>
> +
> +description: |
> + Apple SoCs can have their memory controller performance adjusted depending on
> + system requirements. These performance states are represented by specific
> + memory controller register values. The apple-mcc driver uses these values
> + to change the MCC performance.
> +
> +allOf:
> + - $ref: opp-v2-base.yaml#
> +
> +properties:
> + compatible:
> + const: apple,mcc-operating-points
> +
> +required:
> + - compatible
> +
> +patternProperties:
> + "opp[0-9]+":
> + type: object
> +
> + properties:
> + opp-level: true

You don't need to mention it.

> + apple,memory-perf-config:
> + $ref: /schemas/types.yaml#/definitions/uint32-array
> + description: |
> + A pair of register values used to configure this performance state.
> + minItems: 2
> + maxItems: 2
> +
> + required:
> + - opp-level
> + - apple,memory-perf-config
> +
> + unevaluatedProperties: false
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + mcc_opp: opp-table-2 {
> + compatible = "operating-points-v2";

Different compatible.

> +
> + mcc_lowperf: opp0 {
> + opp-level = <0>;
> + apple,memory-perf-config = <0x813057f 0x1800180>;
> + };
> + mcc_highperf: opp1 {
> + opp-level = <1>;
> + apple,memory-perf-config = <0x133 0x55555340>;
> + };
> + };
>


Best regards,
Krzysztof