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Message-ID: <c7bd9bcb-77a1-9f2d-fe93-afefac5e6def@tronnes.org>
Date:   Sat, 24 Sep 2022 20:06:17 +0200
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Subject: Re: [PATCH v2 02/33] drm/tests: Add Kunit Helpers
To:     Maxime Ripard <maxime@cerno.tech>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        David Airlie <airlied@linux.ie>,
        Maxime Ripard <mripard@kernel.org>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Emma Anholt <emma@anholt.net>,
        Karol Herbst <kherbst@redhat.com>,
        Samuel Holland <samuel@sholland.org>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Daniel Vetter <daniel@ffwll.ch>, Lyude Paul <lyude@redhat.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        Chen-Yu Tsai <wens@csie.org>
Cc:     Hans de Goede <hdegoede@redhat.com>, nouveau@lists.freedesktop.org,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Phil Elwell <phil@raspberrypi.com>,
        intel-gfx@lists.freedesktop.org, Dom Cobley <dom@raspberrypi.com>,
        linux-sunxi@lists.linux.dev,
        Mateusz Kwiatkowski <kfyatek+publicgit@gmail.com>,
        dri-devel@lists.freedesktop.org,
        =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>
References: <20220728-rpi-analog-tv-properties-v2-0-f733a0ed9f90@cerno.tech>
 <20220728-rpi-analog-tv-properties-v2-2-f733a0ed9f90@cerno.tech>
 <3f7000ab-b845-a7e8-f215-02121da779b7@tronnes.org>
From:   =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>
In-Reply-To: <3f7000ab-b845-a7e8-f215-02121da779b7@tronnes.org>
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Den 24.09.2022 19.56, skrev Noralf Trønnes:
> 
> 
> Den 22.09.2022 16.25, skrev Maxime Ripard:
>> As the number of kunit tests in KMS grows further, we start to have
>> multiple test suites that, for example, need to register a mock DRM
>> driver to interact with the KMS function they are supposed to test.
>>
>> Let's add a file meant to provide those kind of helpers to avoid
>> duplication.
>>
>> Signed-off-by: Maxime Ripard <maxime@cerno.tech>
>>
>> diff --git a/drivers/gpu/drm/tests/Makefile b/drivers/gpu/drm/tests/Makefile
>> index 2d9f49b62ecb..b29ef1085cad 100644
>> --- a/drivers/gpu/drm/tests/Makefile
>> +++ b/drivers/gpu/drm/tests/Makefile
>> @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_KUNIT_TEST) += \
>>  	drm_format_helper_test.o \
>>  	drm_format_test.o \
>>  	drm_framebuffer_test.o \
>> +	drm_kunit_helpers.o \
>>  	drm_mm_test.o \
>>  	drm_plane_helper_test.o \
>>  	drm_rect_test.o
>> diff --git a/drivers/gpu/drm/tests/drm_kunit_helpers.c b/drivers/gpu/drm/tests/drm_kunit_helpers.c
>> new file mode 100644
>> index 000000000000..7ebd620481c1
>> --- /dev/null
>> +++ b/drivers/gpu/drm/tests/drm_kunit_helpers.c
>> @@ -0,0 +1,54 @@
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_managed.h>
>> +
>> +#include <linux/device.h>
>> +
>> +static const struct drm_mode_config_funcs drm_mode_config_funcs = {
>> +};
>> +
>> +static const struct drm_driver drm_mode_driver = {
>> +};
>> +
>> +static void drm_kunit_free_device(struct drm_device *drm, void *ptr)
>> +{
>> +	struct device *dev = ptr;
>> +
>> +	root_device_unregister(dev);
>> +}
>> +
>> +struct drm_device *drm_kunit_device_init(const char *name)
>> +{
>> +	struct drm_device *drm;
>> +	struct device *dev;
>> +	int ret;
>> +
>> +	dev = root_device_register(name);
>> +	if (IS_ERR(dev))
>> +		return ERR_CAST(dev);
>> +
>> +	drm = drm_dev_alloc(&drm_mode_driver, dev);
> 
> I can't find drm being freed anywhere?
> Maybe you could assign it to drm->managed.final_kfree.
> 

Perhaps a better solution would be to use devm_drm_dev_alloc() and
unregister the root device on exit. That avoids reaching into the drm
managed internals and it looks more like a regular driver.

> Noralf.
> 
>> +	if (IS_ERR(drm)) {
>> +		root_device_unregister(dev);
>> +		return ERR_CAST(drm);
>> +	}
>> +	drm->mode_config.funcs = &drm_mode_config_funcs;
>> +
>> +	ret = drmm_add_action_or_reset(drm, drm_kunit_free_device, dev);
>> +	if (ret)
>> +		goto err_put_device;
>> +
>> +	ret = drmm_mode_config_init(drm);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	return drm;
>> +
>> +err_put_device:
>> +	drm_dev_put(drm);
>> +	return ERR_PTR(ret);
>> +}
>> +
>> +void drm_kunit_device_exit(struct drm_device *drm)
>> +{
>> +	drm_dev_put(drm);
>> +}
>> diff --git a/drivers/gpu/drm/tests/drm_kunit_helpers.h b/drivers/gpu/drm/tests/drm_kunit_helpers.h
>> new file mode 100644
>> index 000000000000..5015a327a8c1
>> --- /dev/null
>> +++ b/drivers/gpu/drm/tests/drm_kunit_helpers.h
>> @@ -0,0 +1,9 @@
>> +#ifndef DRM_KUNIT_HELPERS_H_
>> +#define DRM_KUNIT_HELPERS_H_
>> +
>> +struct drm_device;
>> +
>> +struct drm_device *drm_kunit_device_init(const char *name);
>> +void drm_kunit_device_exit(struct drm_device *drm);
>> +
>> +#endif // DRM_KUNIT_HELPERS_H_
>>