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Jocelyn Falempe
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drm/panic: Add kunit tests for drm_panic
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. Reviewed-by: Maxime Ripard <mripard@kernel.org> Link: https://patch.msgid.link/20251216082524.115980-3-jfalempe@redhat.com Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
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‎MAINTAINERS‎

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@@ -8749,6 +8749,7 @@ T: git https://gitlab.freedesktop.org/drm/misc/kernel.git
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F: drivers/gpu/drm/drm_draw.c
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F: drivers/gpu/drm/drm_draw_internal.h
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F: drivers/gpu/drm/drm_panic*.c
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F: drivers/gpu/drm/tests/drm_panic_test.c
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F: include/drm/drm_panic*
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DRM PANIC QR CODE

‎drivers/gpu/drm/drm_panic.c‎

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@@ -1084,3 +1084,7 @@ void drm_panic_exit(void)
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{
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drm_panic_qr_exit();
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}
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#ifdef CONFIG_DRM_KUNIT_TEST
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#include "tests/drm_panic_test.c"
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#endif

‎drivers/gpu/drm/tests/drm_panic_test.c‎

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// SPDX-License-Identifier: GPL-2.0 or MIT
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/*
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* Copyright (c) 2025 Red Hat.
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* Author: Jocelyn Falempe <jfalempe@redhat.com>
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*
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* KUNIT tests for drm panic
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*/
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#include <drm/drm_fourcc.h>
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#include <drm/drm_panic.h>
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#include <kunit/test.h>
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#include <linux/units.h>
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#include <linux/vmalloc.h>
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/* Check the framebuffer color only if the panic colors are the default */
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#if (CONFIG_DRM_PANIC_BACKGROUND_COLOR == 0 && \
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CONFIG_DRM_PANIC_FOREGROUND_COLOR == 0xffffff)
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static void drm_panic_check_color_byte(struct kunit *test, u8 b)
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{
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KUNIT_EXPECT_TRUE(test, (b == 0 || b == 0xff));
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}
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#else
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static void drm_panic_check_color_byte(struct kunit *test, u8 b) {}
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#endif
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struct drm_test_mode {
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const int width;
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const int height;
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const u32 format;
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void (*draw_screen)(struct drm_scanout_buffer *sb);
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const char *fname;
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};
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/*
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* Run all tests for the 3 panic screens: user, kmsg and qr_code
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*/
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#define DRM_TEST_MODE_LIST(func) \
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DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_XRGB8888, func) \
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DRM_PANIC_TEST_MODE(300, 200, DRM_FORMAT_XRGB8888, func) \
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DRM_PANIC_TEST_MODE(1920, 1080, DRM_FORMAT_XRGB8888, func) \
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DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB565, func) \
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DRM_PANIC_TEST_MODE(1024, 768, DRM_FORMAT_RGB888, func) \
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#define DRM_PANIC_TEST_MODE(w, h, f, name) { \
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.width = w, \
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.height = h, \
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.format = f, \
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.draw_screen = draw_panic_screen_##name, \
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.fname = #name, \
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}, \
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static const struct drm_test_mode drm_test_modes_cases[] = {
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DRM_TEST_MODE_LIST(user)
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DRM_TEST_MODE_LIST(kmsg)
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#if IS_ENABLED(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
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DRM_TEST_MODE_LIST(qr_code)
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#endif
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};
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#undef DRM_PANIC_TEST_MODE
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static int drm_test_panic_init(struct kunit *test)
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{
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struct drm_scanout_buffer *priv;
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priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
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KUNIT_ASSERT_NOT_NULL(test, priv);
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test->priv = priv;
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drm_panic_set_description("Kunit testing");
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return 0;
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}
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/*
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* Test drawing the panic screen, using a memory mapped framebuffer
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* Set the whole buffer to 0xa5, and then check that all pixels have been
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* written.
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*/
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static void drm_test_panic_screen_user_map(struct kunit *test)
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{
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struct drm_scanout_buffer *sb = test->priv;
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const struct drm_test_mode *params = test->param_value;
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char *fb;
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int fb_size;
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int i;
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sb->format = drm_format_info(params->format);
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fb_size = params->width * params->height * sb->format->cpp[0];
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fb = vmalloc(fb_size);
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KUNIT_ASSERT_NOT_NULL(test, fb);
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memset(fb, 0xa5, fb_size);
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iosys_map_set_vaddr(&sb->map[0], fb);
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sb->width = params->width;
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sb->height = params->height;
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sb->pitch[0] = params->width * sb->format->cpp[0];
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params->draw_screen(sb);
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for (i = 0; i < fb_size; i++)
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drm_panic_check_color_byte(test, fb[i]);
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vfree(fb);
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}
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/*
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* Test drawing the panic screen, using a list of pages framebuffer
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* Set the whole buffer to 0xa5, and then check that all pixels have been
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* written.
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*/
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static void drm_test_panic_screen_user_page(struct kunit *test)
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{
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struct drm_scanout_buffer *sb = test->priv;
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const struct drm_test_mode *params = test->param_value;
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int fb_size, p, i, npages;
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struct page **pages;
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u8 *vaddr;
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sb->format = drm_format_info(params->format);
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fb_size = params->width * params->height * sb->format->cpp[0];
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npages = DIV_ROUND_UP(fb_size, PAGE_SIZE);
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pages = kmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
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KUNIT_ASSERT_NOT_NULL(test, pages);
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for (p = 0; p < npages; p++) {
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pages[p] = alloc_page(GFP_KERNEL);
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if (!pages[p]) {
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npages = p - 1;
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KUNIT_FAIL(test, "Can't allocate page\n");
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goto free_pages;
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}
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vaddr = kmap_local_page(pages[p]);
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memset(vaddr, 0xa5, PAGE_SIZE);
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kunmap_local(vaddr);
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}
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sb->pages = pages;
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sb->width = params->width;
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sb->height = params->height;
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sb->pitch[0] = params->width * sb->format->cpp[0];
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params->draw_screen(sb);
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for (p = 0; p < npages; p++) {
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int bytes_in_page = (p == npages - 1) ? fb_size - p * PAGE_SIZE : PAGE_SIZE;
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vaddr = kmap_local_page(pages[p]);
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for (i = 0; i < bytes_in_page; i++)
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drm_panic_check_color_byte(test, vaddr[i]);
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kunmap_local(vaddr);
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}
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free_pages:
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for (p = 0; p < npages; p++)
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__free_page(pages[p]);
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kfree(pages);
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}
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static void drm_test_panic_set_pixel(struct drm_scanout_buffer *sb,
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unsigned int x,
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unsigned int y,
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u32 color)
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{
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struct kunit *test = (struct kunit *)sb->private;
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KUNIT_ASSERT_TRUE(test, x < sb->width && y < sb->height);
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}
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/*
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* Test drawing the panic screen, using the set_pixel callback
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* Check that all calls to set_pixel() are within the framebuffer
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*/
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static void drm_test_panic_screen_user_set_pixel(struct kunit *test)
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{
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struct drm_scanout_buffer *sb = test->priv;
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const struct drm_test_mode *params = test->param_value;
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sb->format = drm_format_info(params->format);
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sb->set_pixel = drm_test_panic_set_pixel;
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sb->width = params->width;
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sb->height = params->height;
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sb->private = test;
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params->draw_screen(sb);
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}
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static void drm_test_panic_desc(const struct drm_test_mode *t, char *desc)
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{
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sprintf(desc, "Panic screen %s, mode: %d x %d \t%p4cc",
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t->fname, t->width, t->height, &t->format);
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}
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KUNIT_ARRAY_PARAM(drm_test_panic_screen_user_map, drm_test_modes_cases, drm_test_panic_desc);
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KUNIT_ARRAY_PARAM(drm_test_panic_screen_user_page, drm_test_modes_cases, drm_test_panic_desc);
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KUNIT_ARRAY_PARAM(drm_test_panic_screen_user_set_pixel, drm_test_modes_cases, drm_test_panic_desc);
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static struct kunit_case drm_panic_screen_user_test[] = {
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KUNIT_CASE_PARAM(drm_test_panic_screen_user_map,
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drm_test_panic_screen_user_map_gen_params),
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KUNIT_CASE_PARAM(drm_test_panic_screen_user_page,
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drm_test_panic_screen_user_page_gen_params),
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KUNIT_CASE_PARAM(drm_test_panic_screen_user_set_pixel,
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drm_test_panic_screen_user_set_pixel_gen_params),
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{ }
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};
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static struct kunit_suite drm_panic_suite = {
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.name = "drm_panic",
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.init = drm_test_panic_init,
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.test_cases = drm_panic_screen_user_test,
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};
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kunit_test_suite(drm_panic_suite);

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