diff --git a/drivers/gpu/drm/vkms/tests/vkms_color_tests.c b/drivers/gpu/drm/vkms/tests/vkms_color_tests.c
index ad4c2f72fd1e..3eaa2233afbb 100644
--- a/drivers/gpu/drm/vkms/tests/vkms_color_tests.c
+++ b/drivers/gpu/drm/vkms/tests/vkms_color_tests.c
@@ -3,6 +3,7 @@
 #include <kunit/test.h>
 
 #include <drm/drm_fixed.h>
+#include <drm/drm_mode.h>
 
 #define TEST_LUT_SIZE 16
 
@@ -80,11 +81,268 @@ static void vkms_color_srgb_inv_srgb(struct kunit *test)
 	}
 }
 
+#define FIXPT_HALF        (DRM_FIXED_ONE >> 1)
+#define FIXPT_QUARTER     (DRM_FIXED_ONE >> 2)
+
+const struct drm_color_ctm_3x4 test_matrix_3x4_50_desat = { {
+	FIXPT_HALF, FIXPT_QUARTER, FIXPT_QUARTER, 0,
+	FIXPT_QUARTER, FIXPT_HALF, FIXPT_QUARTER, 0,
+	FIXPT_QUARTER, FIXPT_QUARTER, FIXPT_HALF, 0
+} };
+
+static void vkms_color_ctm_3x4_50_desat(struct kunit *test)
+{
+	struct pixel_argb_s32 ref, out;
+
+	/* full white */
+	ref.a = 0x0;
+	ref.r = 0xffff;
+	ref.g = 0xffff;
+	ref.b = 0xffff;
+
+	memcpy(&out, &ref, sizeof(out));
+	apply_3x4_matrix(&out, &test_matrix_3x4_50_desat);
+
+	KUNIT_EXPECT_MEMEQ(test, &ref, &out, sizeof(out));
+
+	/* full black */
+	ref.a = 0x0;
+	ref.r = 0x0;
+	ref.g = 0x0;
+	ref.b = 0x0;
+
+	memcpy(&out, &ref, sizeof(out));
+	apply_3x4_matrix(&out, &test_matrix_3x4_50_desat);
+
+	KUNIT_EXPECT_MEMEQ(test, &ref, &out, sizeof(out));
+
+	/* 50% grey */
+	ref.a = 0x0;
+	ref.r = 0x8000;
+	ref.g = 0x8000;
+	ref.b = 0x8000;
+
+	memcpy(&out, &ref, sizeof(out));
+	apply_3x4_matrix(&out, &test_matrix_3x4_50_desat);
+
+	KUNIT_EXPECT_MEMEQ(test, &ref, &out, sizeof(out));
+
+	/* full red to 50% desat */
+	ref.a = 0x0;
+	ref.r = 0x7fff;
+	ref.g = 0x3fff;
+	ref.b = 0x3fff;
+
+	out.a = 0x0;
+	out.r = 0xffff;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_50_desat);
+
+	KUNIT_EXPECT_MEMEQ(test, &ref, &out, sizeof(out));
+}
+
+const struct drm_color_ctm_3x4 test_matrix_3x4_bt709_enc = { {
+	0x00000000366cf400ull, 0x00000000b7175900ull, 0x0000000127bb300ull, 0,
+	0x800000001993b3a0ull, 0x800000005609fe80ull, 0x000000006f9db200ull, 0,
+	0x000000009d70a400ull, 0x800000008f011100ull, 0x800000000e6f9330ull, 0
+} };
+
+static void vkms_color_ctm_3x4_bt709(struct kunit *test)
+{
+	struct pixel_argb_s32 ref, out;
+
+	/* full white to bt709 */
+	ref.a = 0x0;
+	ref.r = 0xfffe; /* off by one in 16bpc not a big deal */
+	ref.g = 0x0;
+	ref.b = 0x0;
+
+	out.a = 0x0;
+	out.r = 0xffff;
+	out.g = 0xffff;
+	out.b = 0xffff;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 255 */
+	KUNIT_EXPECT_GT(test, out.r, 0xfe00);
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* full black to bt709 */
+	ref.a = 0x0;
+	ref.r = 0x0; /* off by one in 16bpc not a big deal */
+	ref.g = 0x0;
+	ref.b = 0x0;
+
+	out.a = 0x0;
+	out.r = 0x0;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 0 */
+	KUNIT_EXPECT_LT(test, out.r, 0x100);
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* gray to bt709 */
+	ref.a = 0x0;
+	ref.r = 0x7fff; /* off by one in 16bpc not a big deal */
+	ref.g = 0x0;
+	ref.b = 0x0;
+
+	out.a = 0x0;
+	out.r = 0x7fff;
+	out.g = 0x7fff;
+	out.b = 0x7fff;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 127 */
+	KUNIT_EXPECT_GT(test, out.r, 0x7e00);
+	KUNIT_EXPECT_LT(test, out.r, 0x8000);
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* == red 255 - bt709 enc == */
+	out.a = 0x0;
+	out.r = 0xffff;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 54 */
+	KUNIT_EXPECT_GT(test, out.r, 0x3500);
+	KUNIT_EXPECT_LT(test, out.r, 0x3700);
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* blue 157 */
+	KUNIT_EXPECT_GT(test, out.b, 0x9C00);
+	KUNIT_EXPECT_LT(test, out.b, 0x9E00);
+
+
+	/* == green 255 - bt709 enc == */
+	out.a = 0x0;
+	out.r = 0x0;
+	out.g = 0xffff;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 182 */
+	KUNIT_EXPECT_GT(test, out.r, 0xB500);
+	KUNIT_EXPECT_LT(test, out.r, 0xB780); /* laxed by half*/
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* == blue 255 - bt709 enc == */
+	out.a = 0x0;
+	out.r = 0x0;
+	out.g = 0x0;
+	out.b = 0xffff;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 18 */
+	KUNIT_EXPECT_GT(test, out.r, 0x1100);
+	KUNIT_EXPECT_LT(test, out.r, 0x1300);
+
+	/* green 111 */
+	KUNIT_EXPECT_GT(test, out.g, 0x6E00);
+	KUNIT_EXPECT_LT(test, out.g, 0x7000);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* == red 140 - bt709 enc == */
+	out.a = 0x0;
+	out.r = 0x8c8c;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 30 */
+	KUNIT_EXPECT_GT(test, out.r, 0x1D00);
+	KUNIT_EXPECT_LT(test, out.r, 0x1F00);
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x100);
+
+	/* blue 87 */
+	KUNIT_EXPECT_GT(test, out.b, 0x5600);
+	KUNIT_EXPECT_LT(test, out.b, 0x5800);
+
+	/* == green 140 - bt709 enc == */
+	out.a = 0x0;
+	out.r = 0x0;
+	out.g = 0x8c8c;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 30 */
+	KUNIT_EXPECT_GT(test, out.r, 0x6400);
+	KUNIT_EXPECT_LT(test, out.r, 0x6600);
+
+	/* green 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x100);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x100);
+
+
+	/* == blue 140 - bt709 enc == */
+	out.a = 0x0;
+	out.r = 0x0;
+	out.g = 0x0;
+	out.b = 0x8c8c;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* red 30 */
+	KUNIT_EXPECT_GT(test, out.r, 0x900);
+	KUNIT_EXPECT_LT(test, out.r, 0xB00);
+
+	/* green 61 */
+	KUNIT_EXPECT_GT(test, out.g, 0x3C00);
+	KUNIT_EXPECT_LT(test, out.g, 0x3E00);
+
+	/* blue 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x100);
+
+}
+
 static struct kunit_case vkms_color_test_cases[] = {
 	KUNIT_CASE(vkms_color_test_get_lut_index),
 	KUNIT_CASE(vkms_color_test_lerp),
 	KUNIT_CASE(vkms_color_test_linear),
 	KUNIT_CASE(vkms_color_srgb_inv_srgb),
+	KUNIT_CASE(vkms_color_ctm_3x4_50_desat),
+	KUNIT_CASE(vkms_color_ctm_3x4_bt709),
 	{}
 };
 
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index c278fb223188..4ead5346007a 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -164,7 +164,7 @@ static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buff
 	}
 }
 
-static void apply_3x4_matrix(struct pixel_argb_s32 *pixel, const struct drm_color_ctm_3x4 *matrix)
+void apply_3x4_matrix(struct pixel_argb_s32 *pixel, const struct drm_color_ctm_3x4 *matrix)
 {
 	s64 rf, gf, bf;
 
