linux-kernel - Re: [PATCH 05/13] dt-bindings: perf: stm32: introduce DDRPERFM dt-bindings

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Message-ID: <868b20f0-c1ff-4cd7-91bc-e73069aafa95@kernel.org>
Date: Mon, 23 Jun 2025 11:48:57 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Clément Le Goffic <clement.legoffic@...s.st.com>,
 Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Maxime Coquelin <mcoquelin.stm32@...il.com>,
 Alexandre Torgue <alexandre.torgue@...s.st.com>,
 Philipp Zabel <p.zabel@...gutronix.de>, Jonathan Corbet <corbet@....net>,
 Gatien Chevallier <gatien.chevallier@...s.st.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Gabriel Fernandez <gabriel.fernandez@...s.st.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-perf-users@...r.kernel.org,
 devicetree@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-clk@...r.kernel.org
Subject: Re: [PATCH 05/13] dt-bindings: perf: stm32: introduce DDRPERFM
 dt-bindings

On 23/06/2025 11:27, Clément Le Goffic wrote:
> DDRPERFM is the DDR Performance Monitor embedded in STM32MPU SoC.
> It allows to monitor DDR events that come from the DDR Controller
> such as read or write events.
> 

A nit, subject: drop second/last, redundant "bindings". The
"dt-bindings" prefix is already stating that these are bindings.
See also:
https://elixir.bootlin.com/linux/v6.7-rc8/source/Documentation/devicetree/bindings/submitting-patches.rst#L18

> Signed-off-by: Clément Le Goffic <clement.legoffic@...s.st.com>
> ---
>  .../devicetree/bindings/perf/st,stm32-ddr-pmu.yaml | 93 ++++++++++++++++++++++
>  1 file changed, 93 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/perf/st,stm32-ddr-pmu.yaml b/Documentation/devicetree/bindings/perf/st,stm32-ddr-pmu.yaml
> new file mode 100644
> index 000000000000..35d34782865b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/perf/st,stm32-ddr-pmu.yaml
> @@ -0,0 +1,93 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/perf/st,stm32-ddr-pmu.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +maintainers:
> +  - Clément Le Goffic <clement.legoffic@...s.st.com>
> +
> +title: STMicroelectronics STM32 DDR Performance Monitor (DDRPERFM)
> +
> +properties:
> +  compatible:
> +    enum:
> +      - st,stm32mp131-ddr-pmu
> +      - st,stm32mp151-ddr-pmu

These are compatible, aren't they?

> +      - st,stm32mp251-ddr-pmu
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    description: Reference clock for the DDR Performance Monitor

Drop description, obvious.

> +    maxItems: 1
> +
> +  resets:
> +    description: Reset control for the DDR Performance Monitor

Drop description, obvious.


> +    maxItems: 1
> +
> +  access-controllers:
> +    minItems: 1
> +    maxItems: 2
> +
> +  st,dram-type:
> +    description: |
> +      This property is used to specify the type of DRAM memory connected to the
> +      associated memory controller. It is required for the DDR Performance Monitor
> +      to correctly interpret the performance data.
> +      0 = LPDDR4,
> +      1 = LPDDR3,
> +      2 = DDR4,
> +      3 = DDR3
> +    $ref: /schemas/types.yaml#/definitions/uint32

No, use standard JEDEC memory bindings (memory controllers) if you need
to describe the memory, otherwise you duplicate that binding and
duplicate the memory information.

> +    enum: [0, 1, 2, 3]
> +
> +required:
> +  - compatible
> +  - reg
> +
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - st,stm32mp131-ddr-pmu
> +              - st,stm32mp151-ddr-pmu
> +    then:
> +      required:
> +        - clocks
> +        - resets
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: st,stm32mp251-ddr-pmu
> +    then:
> +      required:
> +        - access-controllers
> +        - st,dram-type
> +
> +additionalProperties: false
Best regards,
Krzysztof