Re: [PATCH 4/4] dt-binding:perf: Add Amlogic DDR PMU

Robin Murphy
2022-07-12T12:54:45Z

On 2022-07-12 07:36, Jiucheng Xu wrote:
> Add binding documentation for the Amlogic G12 series DDR
> performance monitor unit.
>
> Signed-off-by: Jiucheng Xu <jiucheng.xu@amlogic.com>
> ---
> .../devicetree/bindings/perf/aml-ddr-pmu.yaml | 51 +++++++++++++++++++
> MAINTAINERS | 1 +
> 2 files changed, 52 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/perf/aml-ddr-pmu.yaml
>
> diff --git a/Documentation/devicetree/bindings/perf/aml-ddr-pmu.yaml b/Documentation/devicetree/bindings/perf/aml-ddr-pmu.yaml
> new file mode 100644
> index 000000000000..c586b4ab4009
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/perf/aml-ddr-pmu.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/perf/aml-ddr-pmu.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Amlogic G12 DDR performance monitor
> +
> +maintainers:
> + - Jiucheng Xu <jiucheng.xu@amlogic.com>
> +
> +properties:
> + compatible:
> + oneOf:
> + - enum:
> + - aml,g12-ddr-pmu
> + - items:
> + - enum:
> + - aml,g12-ddr-pmu
> + - const: aml,g12-ddr-pmu

Judging by what the driver actually implements, this should probably be:

compatible:
items:
- enum:
- amlogic,g12a-ddr-pmu
- amlogic,g12b-ddr-pmu
- amlogic,sm1-ddr-pmu
- const: amlogic,g12-ddr-pmu

There doesn't seem much point in allowing only the common compatible
without a SoC-specific identifier. Note also that "aml," is not the
documented vendor prefix.

> +
> + reg:
> + maxItems: 2
> +
> + interrupts:
> + maxItems: 1
> +
> +required:
> + - compatible
> + - model

Remove this, and use the compatible strings properly as above.

> + - dmc_nr
> + - chann_nr

I suspect those could probably be inferred from the correct compatible
string, but if not (i.e. within one SoC you have multiple PMUs
supporting the same events but with different numbers of usable
channels), then document what exactly they mean.

> + - reg
> + - interrupts
> + - interrupt-names

As mentioned in the driver review, if you really want to use a named
interrupt (which should usually be unnecessary when there's only one),
it has to be a defined name. DT is not a mechanism for overriding what
Linux shows in /proc/interrupts.

Thanks,
Robin.

> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + ddr_pmu: ddr_pmu {
> + compatible = "amlogic,g12-ddr-pmu";
> + model = "g12a";
> + dmc_nr = <1>;
> + chann_nr = <4>;
> + reg = <0x0 0xff638000 0x0 0x100
> + 0x0 0xff638c00 0x0 0x100>;
> + interrupts = <GIC_SPI 52 IRQ_TYPE_EDGE_RISING>;
> + interrupt-names = "ddr_pmu";
> + };
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fd2a56a339b4..ac0a1df4622d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1055,6 +1055,7 @@ M: Jiucheng Xu <jiucheng.xu@amlogic.com>
> S: Supported
> W: http://www.amlogic.com
> F: Documentation/admin-guide/perf/aml-ddr-pmu.rst
> +F: Documentation/devicetree/bindings/perf/aml-ddr-pmu.yaml
> F: drivers/perf/amlogic/
> F: include/soc/amlogic/
>