Add kunit tests for drm_panic.
They check that drawing the panic screen doesn't crash, but they
don't check the correctness of the resulting image.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
---
 MAINTAINERS                            |   1 +
 drivers/gpu/drm/drm_panic.c            |   4 +
 drivers/gpu/drm/tests/drm_panic_test.c | 164 +++++++++++++++++++++++++
 3 files changed, 169 insertions(+)
 create mode 100644 drivers/gpu/drm/tests/drm_panic_test.c

diff --git a/MAINTAINERS b/MAINTAINERS
index cfa28b3470ab..285d1e27734f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8465,6 +8465,7 @@ T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
 F:	drivers/gpu/drm/drm_draw.c
 F:	drivers/gpu/drm/drm_draw_internal.h
 F:	drivers/gpu/drm/drm_panic*.c
+F:	drivers/gpu/drm/tests/drm_panic_test.c
 F:	include/drm/drm_panic*
 
 DRM PANIC QR CODE
diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
index 1e06e3a18d09..d89812ff1935 100644
--- a/drivers/gpu/drm/drm_panic.c
+++ b/drivers/gpu/drm/drm_panic.c
@@ -986,3 +986,7 @@ void drm_panic_exit(void)
 {
 	drm_panic_qr_exit();
 }
+
+#ifdef CONFIG_DRM_KUNIT_TEST
+#include "tests/drm_panic_test.c"
+#endif
diff --git a/drivers/gpu/drm/tests/drm_panic_test.c b/drivers/gpu/drm/tests/drm_panic_test.c
new file mode 100644
index 000000000000..46ff3e5e0e5d
--- /dev/null
+++ b/drivers/gpu/drm/tests/drm_panic_test.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+/*
+ * Copyright (c) 2025 Red Hat.
+ * Author: Jocelyn Falempe <jfalempe@redhat.com>
+ *
+ * KUNIT tests for drm panic
+ */
+
+#include <drm/drm_fourcc.h>
+#include <drm/drm_panic.h>
+
+#include <kunit/test.h>
+
+#include <linux/units.h>
+#include <linux/vmalloc.h>
+
+struct drm_test_mode {
+	const int width;
+	const int height;
+	const u32 format;
+	void (*draw_screen)(struct drm_scanout_buffer *sb);
+	const char *fname;
+};
+
+/*
+ * Run all tests for the 3 panic screens: user, kmsg and qr_code
+ */
+#define DRM_TEST_MODE_LIST(func) \
+	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_XRGB8888, func) \
+	DRM_PANIC_TEST_MODE(300, 200, DRM_FORMAT_XRGB8888, func) \
+	DRM_PANIC_TEST_MODE(1920, 1080, DRM_FORMAT_XRGB8888, func) \
+	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB565, func) \
+	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB888, func) \
+
+#define DRM_PANIC_TEST_MODE(w, h, f, name) { \
+	.width = w, \
+	.height = h, \
+	.format = f, \
+	.draw_screen = draw_panic_screen_##name, \
+	.fname = #name, \
+	}, \
+
+static const struct drm_test_mode drm_test_modes_cases[] = {
+	DRM_TEST_MODE_LIST(user)
+	DRM_TEST_MODE_LIST(kmsg)
+	DRM_TEST_MODE_LIST(qr_code)
+};
+#undef DRM_PANIC_TEST_MODE
+
+static int drm_test_panic_init(struct kunit *test)
+{
+	struct drm_scanout_buffer *priv;
+
+	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	test->priv = priv;
+
+	drm_panic_set_description("Kunit testing");
+
+	return 0;
+}
+
+static void drm_test_panic_screen_user_map(struct kunit *test)
+{
+	struct drm_scanout_buffer *sb = test->priv;
+	const struct drm_test_mode *params = test->param_value;
+	void *fb;
+	int fb_size;
+
+	sb->format = drm_format_info(params->format);
+	fb_size = params->width * params->height * sb->format->cpp[0];
+
+	fb = vmalloc(fb_size);
+	KUNIT_ASSERT_NOT_NULL(test, fb);
+
+	iosys_map_set_vaddr(&sb->map[0], fb);
+	sb->width = params->width;
+	sb->height = params->height;
+	sb->pitch[0] = params->width * sb->format->cpp[0];
+
+	params->draw_screen(sb);
+	vfree(fb);
+}
+
+static void drm_test_panic_screen_user_page(struct kunit *test)
+{
+	struct drm_scanout_buffer *sb = test->priv;
+	const struct drm_test_mode *params = test->param_value;
+	int fb_size;
+	struct page **pages;
+	int i;
+	int npages;
+
+	sb->format = drm_format_info(params->format);
+	fb_size = params->width * params->height * sb->format->cpp[0];
+	npages = DIV_ROUND_UP(fb_size, PAGE_SIZE);
+
+	pages = kmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, pages);
+
+	for (i = 0; i < npages; i++) {
+		pages[i] = alloc_page(GFP_KERNEL);
+		KUNIT_ASSERT_NOT_NULL(test, pages[i]);
+	}
+	sb->pages = pages;
+	sb->width = params->width;
+	sb->height = params->height;
+	sb->pitch[0] = params->width * sb->format->cpp[0];
+
+	params->draw_screen(sb);
+
+	for (i = 0; i < npages; i++)
+		__free_page(pages[i]);
+	kfree(pages);
+}
+
+static void drm_test_panic_set_pixel(struct drm_scanout_buffer *sb,
+				     unsigned int x,
+				     unsigned int y,
+				     u32 color)
+{
+}
+
+static void drm_test_panic_screen_user_set_pixel(struct kunit *test)
+{
+	struct drm_scanout_buffer *sb = test->priv;
+	const struct drm_test_mode *params = test->param_value;
+
+	sb->format = drm_format_info(params->format);
+	sb->set_pixel = drm_test_panic_set_pixel;
+	sb->width = params->width;
+	sb->height = params->height;
+
+	params->draw_screen(sb);
+}
+
+static void drm_test_panic_desc(const struct drm_test_mode *t, char *desc)
+{
+	sprintf(desc, "Panic screen %s, mode: %d x %d \t%p4cc",
+		t->fname, t->width, t->height, &t->format);
+}
+
+KUNIT_ARRAY_PARAM(drm_test_panic_screen_user_map, drm_test_modes_cases, drm_test_panic_desc);
+KUNIT_ARRAY_PARAM(drm_test_panic_screen_user_page, drm_test_modes_cases, drm_test_panic_desc);
+KUNIT_ARRAY_PARAM(drm_test_panic_screen_user_set_pixel, drm_test_modes_cases, drm_test_panic_desc);
+
+static struct kunit_case drm_panic_screen_user_test[] = {
+	KUNIT_CASE_PARAM(drm_test_panic_screen_user_map,
+			 drm_test_panic_screen_user_map_gen_params),
+	KUNIT_CASE_PARAM(drm_test_panic_screen_user_page,
+			 drm_test_panic_screen_user_page_gen_params),
+	KUNIT_CASE_PARAM(drm_test_panic_screen_user_set_pixel,
+			 drm_test_panic_screen_user_set_pixel_gen_params),
+	{ }
+};
+
+static struct kunit_suite drm_panic_suite = {
+	.name = "drm_panic",
+	.init = drm_test_panic_init,
+	.test_cases = drm_panic_screen_user_test,
+};
+
+kunit_test_suite(drm_panic_suite);
-- 
2.50.1

Hi,

On Thu, Aug 21, 2025 at 11:49:06AM +0200, Jocelyn Falempe wrote:
> Add kunit tests for drm_panic.
> They check that drawing the panic screen doesn't crash, but they
> don't check the correctness of the resulting image.
> 
> Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
> ---
>  MAINTAINERS                            |   1 +
>  drivers/gpu/drm/drm_panic.c            |   4 +
>  drivers/gpu/drm/tests/drm_panic_test.c | 164 +++++++++++++++++++++++++
>  3 files changed, 169 insertions(+)
>  create mode 100644 drivers/gpu/drm/tests/drm_panic_test.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cfa28b3470ab..285d1e27734f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8465,6 +8465,7 @@ T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
>  F:	drivers/gpu/drm/drm_draw.c
>  F:	drivers/gpu/drm/drm_draw_internal.h
>  F:	drivers/gpu/drm/drm_panic*.c
> +F:	drivers/gpu/drm/tests/drm_panic_test.c
>  F:	include/drm/drm_panic*
>  
>  DRM PANIC QR CODE
> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
> index 1e06e3a18d09..d89812ff1935 100644
> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
> @@ -986,3 +986,7 @@ void drm_panic_exit(void)
>  {
>  	drm_panic_qr_exit();
>  }
> +
> +#ifdef CONFIG_DRM_KUNIT_TEST
> +#include "tests/drm_panic_test.c"
> +#endif
> diff --git a/drivers/gpu/drm/tests/drm_panic_test.c b/drivers/gpu/drm/tests/drm_panic_test.c
> new file mode 100644
> index 000000000000..46ff3e5e0e5d
> --- /dev/null
> +++ b/drivers/gpu/drm/tests/drm_panic_test.c
> @@ -0,0 +1,164 @@
> +// SPDX-License-Identifier: GPL-2.0 or MIT
> +/*
> + * Copyright (c) 2025 Red Hat.
> + * Author: Jocelyn Falempe <jfalempe@redhat.com>
> + *
> + * KUNIT tests for drm panic
> + */
> +
> +#include <drm/drm_fourcc.h>
> +#include <drm/drm_panic.h>
> +
> +#include <kunit/test.h>
> +
> +#include <linux/units.h>
> +#include <linux/vmalloc.h>
> +
> +struct drm_test_mode {
> +	const int width;
> +	const int height;
> +	const u32 format;
> +	void (*draw_screen)(struct drm_scanout_buffer *sb);
> +	const char *fname;
> +};
> +
> +/*
> + * Run all tests for the 3 panic screens: user, kmsg and qr_code
> + */
> +#define DRM_TEST_MODE_LIST(func) \
> +	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_XRGB8888, func) \
> +	DRM_PANIC_TEST_MODE(300, 200, DRM_FORMAT_XRGB8888, func) \
> +	DRM_PANIC_TEST_MODE(1920, 1080, DRM_FORMAT_XRGB8888, func) \
> +	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB565, func) \
> +	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB888, func) \
> +
> +#define DRM_PANIC_TEST_MODE(w, h, f, name) { \
> +	.width = w, \
> +	.height = h, \
> +	.format = f, \
> +	.draw_screen = draw_panic_screen_##name, \
> +	.fname = #name, \
> +	}, \
> +
> +static const struct drm_test_mode drm_test_modes_cases[] = {
> +	DRM_TEST_MODE_LIST(user)
> +	DRM_TEST_MODE_LIST(kmsg)
> +	DRM_TEST_MODE_LIST(qr_code)
> +};
> +#undef DRM_PANIC_TEST_MODE
> +
> +static int drm_test_panic_init(struct kunit *test)
> +{
> +	struct drm_scanout_buffer *priv;
> +
> +	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
> +	KUNIT_ASSERT_NOT_NULL(test, priv);
> +
> +	test->priv = priv;
> +
> +	drm_panic_set_description("Kunit testing");
> +
> +	return 0;
> +}
> +
> +static void drm_test_panic_screen_user_map(struct kunit *test)
> +{
> +	struct drm_scanout_buffer *sb = test->priv;
> +	const struct drm_test_mode *params = test->param_value;
> +	void *fb;
> +	int fb_size;
> +
> +	sb->format = drm_format_info(params->format);
> +	fb_size = params->width * params->height * sb->format->cpp[0];
> +
> +	fb = vmalloc(fb_size);
> +	KUNIT_ASSERT_NOT_NULL(test, fb);
> +
> +	iosys_map_set_vaddr(&sb->map[0], fb);
> +	sb->width = params->width;
> +	sb->height = params->height;
> +	sb->pitch[0] = params->width * sb->format->cpp[0];
> +
> +	params->draw_screen(sb);
> +	vfree(fb);
> +}

You need to document what you're testing, and what the expected result
is.

Maxime

On 27/08/2025 11:44, Maxime Ripard wrote:
> Hi,
> 
> On Thu, Aug 21, 2025 at 11:49:06AM +0200, Jocelyn Falempe wrote:
>> Add kunit tests for drm_panic.
>> They check that drawing the panic screen doesn't crash, but they
>> don't check the correctness of the resulting image.
>>
>> Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
>> ---
>>   MAINTAINERS                            |   1 +
>>   drivers/gpu/drm/drm_panic.c            |   4 +
>>   drivers/gpu/drm/tests/drm_panic_test.c | 164 +++++++++++++++++++++++++
>>   3 files changed, 169 insertions(+)
>>   create mode 100644 drivers/gpu/drm/tests/drm_panic_test.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index cfa28b3470ab..285d1e27734f 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -8465,6 +8465,7 @@ T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
>>   F:	drivers/gpu/drm/drm_draw.c
>>   F:	drivers/gpu/drm/drm_draw_internal.h
>>   F:	drivers/gpu/drm/drm_panic*.c
>> +F:	drivers/gpu/drm/tests/drm_panic_test.c
>>   F:	include/drm/drm_panic*
>>   
>>   DRM PANIC QR CODE
>> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
>> index 1e06e3a18d09..d89812ff1935 100644
>> --- a/drivers/gpu/drm/drm_panic.c
>> +++ b/drivers/gpu/drm/drm_panic.c
>> @@ -986,3 +986,7 @@ void drm_panic_exit(void)
>>   {
>>   	drm_panic_qr_exit();
>>   }
>> +
>> +#ifdef CONFIG_DRM_KUNIT_TEST
>> +#include "tests/drm_panic_test.c"
>> +#endif
>> diff --git a/drivers/gpu/drm/tests/drm_panic_test.c b/drivers/gpu/drm/tests/drm_panic_test.c
>> new file mode 100644
>> index 000000000000..46ff3e5e0e5d
>> --- /dev/null
>> +++ b/drivers/gpu/drm/tests/drm_panic_test.c
>> @@ -0,0 +1,164 @@
>> +// SPDX-License-Identifier: GPL-2.0 or MIT
>> +/*
>> + * Copyright (c) 2025 Red Hat.
>> + * Author: Jocelyn Falempe <jfalempe@redhat.com>
>> + *
>> + * KUNIT tests for drm panic
>> + */
>> +
>> +#include <drm/drm_fourcc.h>
>> +#include <drm/drm_panic.h>
>> +
>> +#include <kunit/test.h>
>> +
>> +#include <linux/units.h>
>> +#include <linux/vmalloc.h>
>> +
>> +struct drm_test_mode {
>> +	const int width;
>> +	const int height;
>> +	const u32 format;
>> +	void (*draw_screen)(struct drm_scanout_buffer *sb);
>> +	const char *fname;
>> +};
>> +
>> +/*
>> + * Run all tests for the 3 panic screens: user, kmsg and qr_code
>> + */
>> +#define DRM_TEST_MODE_LIST(func) \
>> +	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_XRGB8888, func) \
>> +	DRM_PANIC_TEST_MODE(300, 200, DRM_FORMAT_XRGB8888, func) \
>> +	DRM_PANIC_TEST_MODE(1920, 1080, DRM_FORMAT_XRGB8888, func) \
>> +	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB565, func) \
>> +	DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB888, func) \
>> +
>> +#define DRM_PANIC_TEST_MODE(w, h, f, name) { \
>> +	.width = w, \
>> +	.height = h, \
>> +	.format = f, \
>> +	.draw_screen = draw_panic_screen_##name, \
>> +	.fname = #name, \
>> +	}, \
>> +
>> +static const struct drm_test_mode drm_test_modes_cases[] = {
>> +	DRM_TEST_MODE_LIST(user)
>> +	DRM_TEST_MODE_LIST(kmsg)
>> +	DRM_TEST_MODE_LIST(qr_code)
>> +};
>> +#undef DRM_PANIC_TEST_MODE
>> +
>> +static int drm_test_panic_init(struct kunit *test)
>> +{
>> +	struct drm_scanout_buffer *priv;
>> +
>> +	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
>> +	KUNIT_ASSERT_NOT_NULL(test, priv);
>> +
>> +	test->priv = priv;
>> +
>> +	drm_panic_set_description("Kunit testing");
>> +
>> +	return 0;
>> +}
>> +
>> +static void drm_test_panic_screen_user_map(struct kunit *test)
>> +{
>> +	struct drm_scanout_buffer *sb = test->priv;
>> +	const struct drm_test_mode *params = test->param_value;
>> +	void *fb;
>> +	int fb_size;
>> +
>> +	sb->format = drm_format_info(params->format);
>> +	fb_size = params->width * params->height * sb->format->cpp[0];
>> +
>> +	fb = vmalloc(fb_size);
>> +	KUNIT_ASSERT_NOT_NULL(test, fb);
>> +
>> +	iosys_map_set_vaddr(&sb->map[0], fb);
>> +	sb->width = params->width;
>> +	sb->height = params->height;
>> +	sb->pitch[0] = params->width * sb->format->cpp[0];
>> +
>> +	params->draw_screen(sb);
>> +	vfree(fb);
>> +}
> 
> You need to document what you're testing, and what the expected result
> is.

Sure, I will add some comments.
I think I can also add a few checks, as this doesn't check the result at 
all.

> 
> Maxime