linux-kernel - Re: [PATCH 2/5] coresight: add coresight Trace NOC driver

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Message-ID: <38996ae8-321b-4239-8fe9-b769fdff296c@kernel.org>
Date: Sat, 22 Feb 2025 11:54:52 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Yuanfang Zhang <quic_yuanfang@...cinc.com>,
 Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach
 <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: kernel@...cinc.com, linux-kernel@...r.kernel.org,
 coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 kernel@....qualcomm.com, linux-arm-msm@...r.kernel.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH 2/5] coresight: add coresight Trace NOC driver

On 21/02/2025 08:40, Yuanfang Zhang wrote:
> Add driver to support Coresight device Trace NOC(Network On Chip).
> Trace NOC is an integration hierarchy which is a replacement of
> Dragonlink configuration. It brings together debug components like
> TPDA, funnel and interconnect Trace Noc.
> 
> It sits in the different subsystem of SOC and aggregates the trace
> and transports to QDSS trace bus.
> 
> Signed-off-by: Yuanfang Zhang <quic_yuanfang@...cinc.com>
> ---
>  drivers/hwtracing/coresight/Kconfig          |  10 ++
>  drivers/hwtracing/coresight/Makefile         |   1 +
>  drivers/hwtracing/coresight/coresight-tnoc.c | 191 +++++++++++++++++++++++++++
>  drivers/hwtracing/coresight/coresight-tnoc.h |  53 ++++++++
>  4 files changed, 255 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index 06f0a7594169c5f03ca5f893b7debd294587de78..712b2469e37610e6fc5f15cedb2535bf570f99aa 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -247,4 +247,14 @@ config CORESIGHT_DUMMY
>  
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called coresight-dummy.
> +
> +config CORESIGHT_TNOC
> +	tristate "Coresight Trace Noc driver"
> +	help
> +	  This driver provides support for Trace NoC component.
> +	  Trace NoC is a interconnect that is used to collect trace from
> +	  various subsystems and transport it QDSS trace sink.It sits in
> +	  the different tiles of SOC and aggregates the trace local to the
> +	  tile and transports it another tile or to QDSS trace sink eventually.
> +
>  endif
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index 4ba478211b318ea5305f9f98dda40a041759f09f..ab1cff8f027495fabe3872d52f8c0877e39f0ea8 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -51,3 +51,4 @@ coresight-cti-y := coresight-cti-core.o	coresight-cti-platform.o \
>  		   coresight-cti-sysfs.o
>  obj-$(CONFIG_ULTRASOC_SMB) += ultrasoc-smb.o
>  obj-$(CONFIG_CORESIGHT_DUMMY) += coresight-dummy.o
> +obj-$(CONFIG_CORESIGHT_TNOC) += coresight-tnoc.o

Why do you keep adding entries to the end instead to some logically
ordered place?

Dummy driver, before tpda (obviously tpda should go after tpdm) and now
this... This is just unnecessarily making simultaneous edits difficult.

> diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..11b9a7fd1efdc9fff7c1e9666bda14acb41786cb
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-tnoc.c
> @@ -0,0 +1,191 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2025 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/amba/bus.h>
> +#include <linux/io.h>
> +#include <linux/coresight.h>
> +#include <linux/of.h>
> +
> +#include "coresight-priv.h"
> +#include "coresight-tnoc.h"
> +#include "coresight-trace-id.h"
> +


> +
> +	drvdata->base = devm_ioremap_resource(dev, &adev->res);
> +	if (!drvdata->base)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&drvdata->spinlock);
> +
> +	ret = trace_noc_init_default_data(drvdata);
> +	if (ret)
> +		return ret;
> +
> +	desc.ops = &trace_noc_cs_ops;
> +	desc.type = CORESIGHT_DEV_TYPE_LINK;
> +	desc.subtype.link_subtype = CORESIGHT_DEV_SUBTYPE_LINK_MERG;
> +	desc.pdata = adev->dev.platform_data;
> +	desc.dev = &adev->dev;
> +	desc.access = CSDEV_ACCESS_IOMEM(drvdata->base);
> +	drvdata->csdev = coresight_register(&desc);
> +	if (IS_ERR(drvdata->csdev))
> +		return PTR_ERR(drvdata->csdev);
> +
> +	pm_runtime_put(&adev->dev);
> +
> +	dev_dbg(drvdata->dev, "Trace Noc initialized\n");


Drop. There is really no need to tell that function finished.

Please run standard kernel tools for static analysis, like coccinelle,
smatch and sparse, and fix reported warnings. Also please check for
warnings when building with W=1. Most of these commands (checks or W=1
build) can build specific targets, like some directory, to narrow the
scope to only your code. The code here looks like it needs a fix. Feel
free to get in touch if the warning is not clear.


Best regards,
Krzysztof