linux-kernel - Re: [PATCH v5 7/7] dt-bindings: Document devicetree binding for ARM SPE

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Date:   Mon, 2 Oct 2017 11:07:00 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Will Deacon <will.deacon@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, marc.zyngier@....com,
        kim.phillips@....com, tglx@...utronix.de, peterz@...radead.org,
        alexander.shishkin@...ux.intel.com, robh@...nel.org,
        suzuki.poulose@....com, pawel.moll@....com,
        mathieu.poirier@...aro.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 7/7] dt-bindings: Document devicetree binding for ARM
 SPE

On Thu, Sep 28, 2017 at 03:09:51PM +0100, Will Deacon wrote:
> This patch documents the devicetree binding in use for ARM SPE.
> 
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Rob Herring <robh@...nel.org>
> Signed-off-by: Will Deacon <will.deacon@....com>
> ---
>  Documentation/devicetree/bindings/arm/spe-pmu.txt | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/spe-pmu.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/spe-pmu.txt b/Documentation/devicetree/bindings/arm/spe-pmu.txt
> new file mode 100644
> index 000000000000..93372f2a7df9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/spe-pmu.txt
> @@ -0,0 +1,20 @@
> +* ARMv8.2 Statistical Profiling Extension (SPE) Performance Monitor Units (PMU)
> +
> +ARMv8.2 introduces the optional Statistical Profiling Extension for collecting
> +performance sample data using an in-memory trace buffer.

It might make sense to comment that even if described in the DT, a
higher exception level may disallow access (discoverable via
PMBIDR_EL1).

Either way:

Acked-by: Mark Rutland <mark.rutland@....com>

As a nit, this should've come before the driver, as per
Documentation/devicetree/bindings/submitting-patches.txt, but thanks for
splitting as its own patch.

Thanks,
Mark.

> +
> +** SPE Required properties:
> +
> +- compatible : should be one of:
> +	       "arm,statistical-profiling-extension-v1"
> +
> +- interrupts : Exactly 1 PPI must be listed. For heterogeneous systems where
> +               SPE is only supported on a subset of the CPUs, please consult
> +	       the arm,gic-v3 binding for details on describing a PPI partition.
> +
> +** Example:
> +
> +spe-pmu {
> +        compatible = "arm,statistical-profiling-extension-v1";
> +        interrupts = <GIC_PPI 05 IRQ_TYPE_LEVEL_HIGH &part1>;
> +};
> -- 
> 2.1.4
>