diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index d684855b95c2..28d059007ac2 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -55,6 +55,7 @@ config DRM_DEBUG_SELFTEST
 	depends on DEBUG_KERNEL
 	select PRIME_NUMBERS
 	select DRM_LIB_RANDOM
+	select DRM_KMS_HELPER
 	default n
 	help
 	  This option provides kernel modules that can be used to run
diff --git a/drivers/gpu/drm/selftests/Makefile b/drivers/gpu/drm/selftests/Makefile
index f7dd66e859a9..9fc349fa18e9 100644
--- a/drivers/gpu/drm/selftests/Makefile
+++ b/drivers/gpu/drm/selftests/Makefile
@@ -1 +1 @@
-obj-$(CONFIG_DRM_DEBUG_SELFTEST) += test-drm_mm.o
+obj-$(CONFIG_DRM_DEBUG_SELFTEST) += test-drm_mm.o test-drm-helper.o
diff --git a/drivers/gpu/drm/selftests/drm_helper_selftests.h b/drivers/gpu/drm/selftests/drm_helper_selftests.h
new file mode 100644
index 000000000000..9771290ed228
--- /dev/null
+++ b/drivers/gpu/drm/selftests/drm_helper_selftests.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* List each unit test as selftest(name, function)
+ *
+ * The name is used as both an enum and expanded as igt__name to create
+ * a module parameter. It must be unique and legal for a C identifier.
+ *
+ * Tests are executed in order by igt/drm_selftests_helper
+ */
+selftest(check_plane_state, igt_check_plane_state)
diff --git a/drivers/gpu/drm/selftests/test-drm-helper.c b/drivers/gpu/drm/selftests/test-drm-helper.c
new file mode 100644
index 000000000000..a015712b43e8
--- /dev/null
+++ b/drivers/gpu/drm/selftests/test-drm-helper.c
@@ -0,0 +1,247 @@
+/*
+ * Test cases for the drm_kms_helper functions
+ */
+
+#define pr_fmt(fmt) "drm_kms_helper: " fmt
+
+#include <linux/module.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_plane_helper.h>
+#include <drm/drm_modes.h>
+
+#define TESTS "drm_helper_selftests.h"
+#include "drm_selftest.h"
+
+#define FAIL(test, msg, ...) \
+	do { \
+		if (test) { \
+			pr_err("%s/%u: " msg, __FUNCTION__, __LINE__, ##__VA_ARGS__); \
+			return -EINVAL; \
+		} \
+	} while (0)
+
+#define FAIL_ON(x) FAIL((x), "%s", "FAIL_ON(" __stringify(x) ")\n")
+
+static void set_src(struct drm_plane_state *plane_state,
+		    unsigned src_x, unsigned src_y,
+		    unsigned src_w, unsigned src_h)
+{
+	plane_state->src_x = src_x;
+	plane_state->src_y = src_y;
+	plane_state->src_w = src_w;
+	plane_state->src_h = src_h;
+}
+
+static bool check_src_eq(struct drm_plane_state *plane_state,
+			 unsigned src_x, unsigned src_y,
+			 unsigned src_w, unsigned src_h)
+{
+	if (plane_state->src.x1 < 0) {
+		pr_err("src x coordinate %x should never be below 0.\n", plane_state->src.x1);
+		drm_rect_debug_print("src: ", &plane_state->src, true);
+		return false;
+	}
+	if (plane_state->src.y1 < 0) {
+		pr_err("src y coordinate %x should never be below 0.\n", plane_state->src.y1);
+		drm_rect_debug_print("src: ", &plane_state->src, true);
+		return false;
+	}
+
+	if (plane_state->src.x1 != src_x ||
+	    plane_state->src.y1 != src_y ||
+	    drm_rect_width(&plane_state->src) != src_w ||
+	    drm_rect_height(&plane_state->src) != src_h) {
+		drm_rect_debug_print("src: ", &plane_state->src, true);
+		return false;
+	}
+
+	return true;
+}
+
+static void set_crtc(struct drm_plane_state *plane_state,
+		     int crtc_x, int crtc_y,
+		     unsigned crtc_w, unsigned crtc_h)
+{
+	plane_state->crtc_x = crtc_x;
+	plane_state->crtc_y = crtc_y;
+	plane_state->crtc_w = crtc_w;
+	plane_state->crtc_h = crtc_h;
+}
+
+static bool check_crtc_eq(struct drm_plane_state *plane_state,
+			  int crtc_x, int crtc_y,
+			  unsigned crtc_w, unsigned crtc_h)
+{
+	if (plane_state->dst.x1 != crtc_x ||
+	    plane_state->dst.y1 != crtc_y ||
+	    drm_rect_width(&plane_state->dst) != crtc_w ||
+	    drm_rect_height(&plane_state->dst) != crtc_h) {
+		drm_rect_debug_print("dst: ", &plane_state->dst, false);
+
+		return false;
+	}
+
+	return true;
+}
+
+static int igt_check_plane_state(void *ignored)
+{
+	int ret;
+
+	const struct drm_crtc_state crtc_state = {
+		.crtc = ZERO_SIZE_PTR,
+		.enable = true,
+		.active = true,
+		.mode = {
+			DRM_MODE("1024x768", 0, 65000, 1024, 1048,
+				1184, 1344, 0, 768, 771, 777, 806, 0,
+				DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC)
+		},
+	};
+	struct drm_framebuffer fb = {
+		.width = 2048,
+		.height = 2048
+	};
+	struct drm_plane_state plane_state = {
+		.crtc = ZERO_SIZE_PTR,
+		.fb = &fb,
+		.rotation = DRM_MODE_ROTATE_0
+	};
+
+	/* Simple clipping, no scaling. */
+	set_src(&plane_state, 0, 0, fb.width << 16, fb.height << 16);
+	set_crtc(&plane_state, 0, 0, fb.width, fb.height);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, false);
+	FAIL(ret < 0, "Simple clipping check should pass\n");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 1024 << 16, 768 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1024, 768));
+
+	/* Rotated clipping + reflection, no scaling. */
+	plane_state.rotation = DRM_MODE_ROTATE_90 | DRM_MODE_REFLECT_X;
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, false);
+	FAIL(ret < 0, "Rotated clipping check should pass\n");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 768 << 16, 1024 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1024, 768));
+	plane_state.rotation = DRM_MODE_ROTATE_0;
+
+	/* Check whether positioning works correctly. */
+	set_src(&plane_state, 0, 0, 1023 << 16, 767 << 16);
+	set_crtc(&plane_state, 0, 0, 1023, 767);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, false);
+	FAIL(!ret, "Should not be able to position on the crtc with can_position=false\n");
+
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  true, false);
+	FAIL(ret < 0, "Simple positioning should work\n");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 1023 << 16, 767 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1023, 767));
+
+	/* Simple scaling tests. */
+	set_src(&plane_state, 0, 0, 512 << 16, 384 << 16);
+	set_crtc(&plane_state, 0, 0, 1024, 768);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  0x8001,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, false);
+	FAIL(!ret, "Upscaling out of range should fail.\n");
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  0x8000,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, false);
+	FAIL(ret < 0, "Upscaling exactly 2x should work\n");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 512 << 16, 384 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1024, 768));
+
+	set_src(&plane_state, 0, 0, 2048 << 16, 1536 << 16);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  0x1ffff, false, false);
+	FAIL(!ret, "Downscaling out of range should fail.\n");
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  0x20000, false, false);
+	FAIL(ret < 0, "Should succeed with exact scaling limit\n");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 2048 << 16, 1536 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1024, 768));
+
+	/* Testing rounding errors. */
+	set_src(&plane_state, 0, 0, 0x40001, 0x40001);
+	set_crtc(&plane_state, 1022, 766, 4, 4);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  0x10001,
+						  true, false);
+	FAIL(ret < 0, "Should succeed by clipping to exact multiple");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 2 << 16, 2 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 1022, 766, 2, 2));
+
+	set_src(&plane_state, 0x20001, 0x20001, 0x4040001, 0x3040001);
+	set_crtc(&plane_state, -2, -2, 1028, 772);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  0x10001,
+						  false, false);
+	FAIL(ret < 0, "Should succeed by clipping to exact multiple");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0x40002, 0x40002, 1024 << 16, 768 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1024, 768));
+
+	set_src(&plane_state, 0, 0, 0x3ffff, 0x3ffff);
+	set_crtc(&plane_state, 1022, 766, 4, 4);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  0xffff,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  true, false);
+	FAIL(ret < 0, "Should succeed by clipping to exact multiple");
+	FAIL_ON(!plane_state.visible);
+	/* Should not be rounded to 0x20001, which would be upscaling. */
+	FAIL_ON(!check_src_eq(&plane_state, 0, 0, 2 << 16, 2 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 1022, 766, 2, 2));
+
+	set_src(&plane_state, 0x1ffff, 0x1ffff, 0x403ffff, 0x303ffff);
+	set_crtc(&plane_state, -2, -2, 1028, 772);
+	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
+						  0xffff,
+						  DRM_PLANE_HELPER_NO_SCALING,
+						  false, false);
+	FAIL(ret < 0, "Should succeed by clipping to exact multiple");
+	FAIL_ON(!plane_state.visible);
+	FAIL_ON(!check_src_eq(&plane_state, 0x3fffe, 0x3fffe, 1024 << 16, 768 << 16));
+	FAIL_ON(!check_crtc_eq(&plane_state, 0, 0, 1024, 768));
+
+	return 0;
+}
+
+#include "drm_selftest.c"
+
+static int __init test_drm_helper_init(void)
+{
+	int err;
+
+	err = run_selftests(selftests, ARRAY_SIZE(selftests), NULL);
+
+	return err > 0 ? 0 : err;
+}
+
+module_init(test_drm_helper_init);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL");
