Re: [PATCH v4] coresight: Add a KUnit test for coresight_find_default_sink()

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 3/12/25 16:01, James Clark wrote:
> Add a test to confirm that default sink selection skips over an ETF
> and returns an ETR even if it's further away.
> 
> This also makes it easier to add new unit tests in the future.

The test overall looks good but there are some comments below.

> 
> Reviewed-by: Leo Yan <leo.yan@arm.com>
> Signed-off-by: James Clark <james.clark@linaro.org>
> ---
> Changes in v4:
> - Rename etm to src now that it's not CORESIGHT_DEV_SUBTYPE_SOURCE_PROC
> - Remove the now empty src_ops too
> - Fix a rebase mistake in the Makefile that removed CTCU
> - Link to v3: https://lore.kernel.org/r/20250312-james-cs-kunit-test-v3-1-dcfb69730161@linaro.org
> 
> Changes in v3:
> - Use CORESIGHT_DEV_SUBTYPE_SOURCE_BUS type instead of the default
>   (CORESIGHT_DEV_SUBTYPE_SOURCE_PROC) so that the test still works even
>   when TRBE sinks are registered. This also removes the need for the
>   fake CPU ID callback.
> - Link to v2: https://lore.kernel.org/r/20250305-james-cs-kunit-test-v2-1-83ba682b976c@linaro.org
> 
> Changes in v2:
> - Let devm free everything rather than doing individual kfrees:
>   "Like with managed drivers, KUnit-managed fake devices are
>   automatically cleaned up when the test finishes, but can be manually
>   cleaned up early with kunit_device_unregister()."
> - Link to v1: https://lore.kernel.org/r/20250225164639.522741-1-james.clark@linaro.org
> ---
>  drivers/hwtracing/coresight/Kconfig                |  9 +++
>  drivers/hwtracing/coresight/Makefile               |  1 +
>  drivers/hwtracing/coresight/coresight-core.c       |  1 +
>  .../hwtracing/coresight/coresight-kunit-tests.c    | 74 ++++++++++++++++++++++
>  4 files changed, 85 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index ecd7086a5b83..f064e3d172b3 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -259,4 +259,13 @@ config CORESIGHT_DUMMY
>  
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called coresight-dummy.
> +
> +config CORESIGHT_KUNIT_TESTS
> +	  tristate "Enable Coresight unit tests"
> +	  depends on KUNIT
> +	  default KUNIT_ALL_TESTS
> +	  help
> +	    Enable Coresight unit tests. Only useful for development and not
> +	    intended for production.

The description sounds adequate given that more unit tests might be added later.

> +
>  endif
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index 8e62c3150aeb..4e6ea5b05b01 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -53,3 +53,4 @@ obj-$(CONFIG_ULTRASOC_SMB) += ultrasoc-smb.o
>  obj-$(CONFIG_CORESIGHT_DUMMY) += coresight-dummy.o
>  obj-$(CONFIG_CORESIGHT_CTCU) += coresight-ctcu.o
>  coresight-ctcu-y := coresight-ctcu-core.o
> +obj-$(CONFIG_CORESIGHT_KUNIT_TESTS) += coresight-kunit-tests.o
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index fb43ef6a3b1f..47af75ba7a00 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -959,6 +959,7 @@ coresight_find_default_sink(struct coresight_device *csdev)
>  	}
>  	return csdev->def_sink;
>  }
> +EXPORT_SYMBOL_GPL(coresight_find_default_sink);

This symbol needs exporting given that the kunit test here can also be built
as a module.

>  
>  static int coresight_remove_sink_ref(struct device *dev, void *data)
>  {
> diff --git a/drivers/hwtracing/coresight/coresight-kunit-tests.c b/drivers/hwtracing/coresight/coresight-kunit-tests.c
> new file mode 100644
> index 000000000000..c8f361767c45
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-kunit-tests.c
> @@ -0,0 +1,74 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <kunit/test.h>
> +#include <kunit/device.h>
> +#include <linux/coresight.h>
> +
> +#include "coresight-priv.h"
> +
> +static struct coresight_device *coresight_test_device(struct device *dev)
> +{
> +	struct coresight_device *csdev = devm_kcalloc(dev, 1,
> +						     sizeof(struct coresight_device),
> +						     GFP_KERNEL);
> +	csdev->pdata = devm_kcalloc(dev, 1,
> +				   sizeof(struct coresight_platform_data),
> +				   GFP_KERNEL);

Guess both these memory allocations gets freed up here automatically
via kunit_device's device framework when the test suit exits ?

> +	return csdev;
> +}
> +
> +static void test_default_sink(struct kunit *test)
> +{
> +	/*
> +	 * Source -> ETF -> ETR -> CATU
> +	 *                   ^
> +	 *                   | default
> +	 */

Should some more random path combinations involving ETR and ETF along with
other coresight devices also be tested where ETR gets selected as default ?

> +	struct device *dev = kunit_device_register(test, "coresight_kunit");
> +	struct coresight_device *src = coresight_test_device(dev),
> +				*etf = coresight_test_device(dev),
> +				*etr = coresight_test_device(dev),
> +				*catu = coresight_test_device(dev);
> +	struct coresight_connection conn = {};
> +
> +	src->type = CORESIGHT_DEV_TYPE_SOURCE;
> +	/*
> +	 * Don't use CORESIGHT_DEV_SUBTYPE_SOURCE_PROC, that would always return
> +	 * a TRBE sink if one is registered.

Probably this should be tested as well i.e when TRBE sink is also available
and it gets picked up as a default.

> +	 */
> +	src->subtype.source_subtype = CORESIGHT_DEV_SUBTYPE_SOURCE_BUS;
> +	etf->type = CORESIGHT_DEV_TYPE_LINKSINK;
> +	etf->subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
> +	etr->type = CORESIGHT_DEV_TYPE_SINK;
> +	etr->subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM;
> +	catu->type = CORESIGHT_DEV_TYPE_HELPER;
> +
> +	conn.src_dev = src;
> +	conn.dest_dev = etf;
> +	coresight_add_out_conn(dev, src->pdata, &conn);
> +
> +	conn.src_dev = etf;
> +	conn.dest_dev = etr;
> +	coresight_add_out_conn(dev, etf->pdata, &conn);
> +
> +	conn.src_dev = etr;
> +	conn.dest_dev = catu;
> +	coresight_add_out_conn(dev, etr->pdata, &conn);
> +
> +	KUNIT_ASSERT_PTR_EQ(test, coresight_find_default_sink(src), etr);
> +}
> +
> +static struct kunit_case coresight_testcases[] = {
> +	KUNIT_CASE(test_default_sink),
> +	{}
> +};
> +
> +static struct kunit_suite coresight_test_suite = {
> +	.name = "coresight_test_suite",
> +	.test_cases = coresight_testcases,
> +};
> +
> +kunit_test_suites(&coresight_test_suite);
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("James Clark <james.clark@linaro.org>");
> +MODULE_DESCRIPTION("Arm CoreSight KUnit tests");
> 
> ---
> base-commit: 3eadce8308bc8d808fd9e3a9d211c84215087451
> change-id: 20250305-james-cs-kunit-test-3af1df2401e6
> 
> Best regards,