Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Sun, 3 Jan 2021 10:05:40 -0700
From:   Rob Herring <robh@kernel.org>
To:     Anshuman Khandual <anshuman.khandual@arm.com>
Cc:     linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
        linux-kernel@vger.kernel.org,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Mike Leach <mike.leach@linaro.org>,
        Linu Cherian <lcherian@marvell.com>, devicetree@vger.kernel.org
Subject: Re: [PATCH 11/11] dts: bindings: Document device tree binding for
 Arm TRBE
Message-ID: <20210103170540.GA4055084@robh.at.kernel.org>
References: <1608717823-18387-1-git-send-email-anshuman.khandual@arm.com>
 <1608717823-18387-12-git-send-email-anshuman.khandual@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1608717823-18387-12-git-send-email-anshuman.khandual@arm.com>
Precedence: bulk

On Wed, Dec 23, 2020 at 03:33:43PM +0530, Anshuman Khandual wrote:
> This patch documents the device tree binding in use for Arm TRBE.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> Changes in V1:
> 
> - TRBE DT entry has been renamed as 'arm, trace-buffer-extension'
> 
>  Documentation/devicetree/bindings/arm/trbe.txt | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/trbe.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/trbe.txt b/Documentation/devicetree/bindings/arm/trbe.txt
> new file mode 100644
> index 0000000..001945d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/trbe.txt
> @@ -0,0 +1,20 @@
> +* Trace Buffer Extension (TRBE)
> +
> +Trace Buffer Extension (TRBE) is used for collecting trace data generated
> +from a corresponding trace unit (ETE) using an in memory trace buffer.
> +
> +** TRBE Required properties:
> +
> +- compatible : should be one of:
> +	       "arm,trace-buffer-extension"
> +
> +- interrupts : Exactly 1 PPI must be listed. For heterogeneous systems where
> +	       TRBE is only supported on a subset of the CPUs, please consult
> +	       the arm,gic-v3 binding for details on describing a PPI partition.
> +
> +** Example:
> +
> +trbe {
> +	compatible = "arm,trace-buffer-extension";
> +	interrupts = <GIC_PPI 15 IRQ_TYPE_LEVEL_HIGH>;

If only an interrupt, then could just be part of ETE? If not, how is 
this hardware block accessed? An interrupt alone is not enough unless 
there's some architected way to access.

Rob