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From: Rob Herring <robh@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: will@kernel.org, mark.rutland@arm.com,
	linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	suzuki.poulose@arm.com, ilkka@os.amperecomputing.com,
	bwicaksono@nvidia.com, YWan@nvidia.com, rwiley@nvidia.com,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>
Subject: Re: [PATCH 4/5] dt-bindings/perf: Add Arm CoreSight PMU
Date: Fri, 8 Dec 2023 13:33:52 -0600	[thread overview]
Message-ID: <20231208193352.GA1865260-robh@kernel.org> (raw)
In-Reply-To: <bbb4262065cfc906f98165cac074e86dce19599e.1701793996.git.robin.murphy@arm.com>

On Tue, Dec 05, 2023 at 04:51:57PM +0000, Robin Murphy wrote:
> Add a binding for implementations of the Arm CoreSight Performance
> Monitoring Unit Architecture. Not to be confused with CoreSight debug
> and trace, the PMU architecture defines a standard MMIO interface for
> event counters similar to the CPU PMU architecture, where the
> implementation and most of its features are discoverable through ID
> registers.

The implementation is separate from the CPU PMU rather than an MMIO view 
of it. Not really clear in my quick read of the spec.

> CC: Rob Herring <robh+dt@kernel.org>
> CC: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> CC: Conor Dooley <conor+dt@kernel.org>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  .../bindings/perf/arm,coresight-pmu.yaml      | 39 +++++++++++++++++++
>  1 file changed, 39 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/perf/arm,coresight-pmu.yaml
> 
> diff --git a/Documentation/devicetree/bindings/perf/arm,coresight-pmu.yaml b/Documentation/devicetree/bindings/perf/arm,coresight-pmu.yaml
> new file mode 100644
> index 000000000000..12c7b28eee35
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/perf/arm,coresight-pmu.yaml
> @@ -0,0 +1,39 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/perf/arm,coresight-pmu.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Arm Coresight Performance Monitoring Unit Architecture
> +
> +maintainers:
> +  - Robin Murphy <robin.murphy@arm.com>
> +
> +properties:
> +  compatible:
> +    const: arm,coresight-pmu
> +
> +  reg:
> +    items:
> +      - description: Register page 0
> +      - description: Register page 1 (if dual-page extension implemented)
> +    minItems: 1
> +
> +  interrupts:
> +    items:
> +      - description: Overflow interrupt
> +
> +  cpus:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array

Don't need a type. Already defined.

> +    minItems: 1

1 is always the minimum.

> +    description: List of CPUs with which the PMU is associated, if applicable

When is it applicable? Presumably when it is associated with only a 
subset of CPUs?

> +
> +  arm,64-bit-atomic:
> +    type: boolean
> +    description: Register accesses are single-copy atomic at doubleword granularity

As this is recommended, shouldn't the property be the inverse.

Maybe the standard 'reg-io-width = <4>' would be sufficient here?

Rob

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  reply	other threads:[~2023-12-08 19:34 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-05 16:51 [PATCH 0/5] perf/arm_cspmu: Add devicetree support Robin Murphy
2023-12-05 16:51 ` [PATCH 1/5] perf/arm_cspmu: Simplify initialisation Robin Murphy
2023-12-07  2:16   ` Ilkka Koskinen
2023-12-05 16:51 ` [PATCH 2/5] perf/arm_cspmu: Simplify attribute groups Robin Murphy
2023-12-07  2:47   ` Ilkka Koskinen
2023-12-05 16:51 ` [PATCH 3/5] perf/arm_cspmu: Simplify counter reset Robin Murphy
2023-12-07  2:15   ` Ilkka Koskinen
2023-12-05 16:51 ` [PATCH 4/5] dt-bindings/perf: Add Arm CoreSight PMU Robin Murphy
2023-12-08 19:33   ` Rob Herring [this message]
2023-12-08 21:56     ` Robin Murphy
2023-12-05 16:51 ` [PATCH 5/5] perf/arm_cspmu: Add devicetree support Robin Murphy
2023-12-06 23:43   ` Ilkka Koskinen
2023-12-07  9:43     ` Robin Murphy
2023-12-08  6:35       ` Ilkka Koskinen

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