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Date:   Mon, 26 Sep 2022 14:15:48 +0200
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Subject: Re: [PATCH v2 02/33] drm/tests: Add Kunit Helpers
To:     Maxime Ripard <maxime@cerno.tech>
Cc:     Jernej Skrabec <jernej.skrabec@gmail.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        David Airlie <airlied@linux.ie>,
        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>,
        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>
 <c7bd9bcb-77a1-9f2d-fe93-afefac5e6def@tronnes.org>
 <20220926093612.wvbou2srbo3uinar@houat>
From:   =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= <noralf@tronnes.org>
In-Reply-To: <20220926093612.wvbou2srbo3uinar@houat>
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Den 26.09.2022 11.36, skrev Maxime Ripard:
> Hi Noralf,
> 
> On Sat, Sep 24, 2022 at 08:06:17PM +0200, Noralf Trønnes wrote:
>> 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.
> 
> There's a drm_dev_put in the test_exit hook which should free it.
> 

I see now, there's a drmm_add_final_kfree() in drm_dev_alloc().

Noralf.

>> 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.
> 
> But yeah, this is a good idea, I'll do it.
> 
> Maxime