drm/vkms: Add tests for CTM handling

A whole slew of tests for CTM handling that greatly helped in
debugging the CTM code. The extent of tests might seem a bit
silly but they're fast and might someday help save someone
else's day when debugging this.

Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patch.msgid.link/20251115000237.3561250-23-alex.hung@amd.com

drivers/gpu/drm/vkms/tests/vkms_color_test.c

@@ -148,11 +148,258 @@ static void vkms_color_srgb_inv_srgb(struct kunit *test)
 	}
 }
 
+#define FIXPT_HALF        (DRM_FIXED_ONE >> 1)
+#define FIXPT_QUARTER     (DRM_FIXED_ONE >> 2)
+
+static 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 = 0xffff;
+	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 = 0xffff;
+	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 = 0xffff;
+	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 = 0xffff;
+	ref.r = 0x8000;
+	ref.g = 0x4000;
+	ref.b = 0x4000;
+
+	out.a = 0xffff;
+	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));
+}
+
+/*
+ * BT.709 encoding matrix
+ *
+ * Values printed from within IGT when converting
+ * igt_matrix_3x4_bt709_enc to the fixed-point format expected
+ * by DRM/KMS.
+ */
+static 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 out;
+
+	/* full white to bt709 */
+	out.a = 0xffff;
+	out.r = 0xffff;
+	out.g = 0xffff;
+	out.b = 0xffff;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 255 */
+	KUNIT_EXPECT_GT(test, out.r, 0xfe00);
+	KUNIT_EXPECT_LT(test, out.r, 0x10000);
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* V 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* full black to bt709 */
+	out.a = 0xffff;
+	out.r = 0x0;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 0 */
+	KUNIT_EXPECT_LT(test, out.r, 0x100);
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* V 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* gray to bt709 */
+	out.a = 0xffff;
+	out.r = 0x7fff;
+	out.g = 0x7fff;
+	out.b = 0x7fff;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 127 */
+	KUNIT_EXPECT_GT(test, out.r, 0x7e00);
+	KUNIT_EXPECT_LT(test, out.r, 0x8000);
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* V 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* == red 255 - bt709 enc == */
+	out.a = 0xffff;
+	out.r = 0xffff;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 54 */
+	KUNIT_EXPECT_GT(test, out.r, 0x3500);
+	KUNIT_EXPECT_LT(test, out.r, 0x3700);
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* V 157 */
+	KUNIT_EXPECT_GT(test, out.b, 0x9C00);
+	KUNIT_EXPECT_LT(test, out.b, 0x9E00);
+
+	/* == green 255 - bt709 enc == */
+	out.a = 0xffff;
+	out.r = 0x0;
+	out.g = 0xffff;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 182 */
+	KUNIT_EXPECT_GT(test, out.r, 0xB500);
+	KUNIT_EXPECT_LT(test, out.r, 0xB780); /* laxed by half*/
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x0100);
+
+	/* V 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* == blue 255 - bt709 enc == */
+	out.a = 0xffff;
+	out.r = 0x0;
+	out.g = 0x0;
+	out.b = 0xffff;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 18 */
+	KUNIT_EXPECT_GT(test, out.r, 0x1100);
+	KUNIT_EXPECT_LT(test, out.r, 0x1300);
+
+	/* U 111 */
+	KUNIT_EXPECT_GT(test, out.g, 0x6E00);
+	KUNIT_EXPECT_LT(test, out.g, 0x7000);
+
+	/* V 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x0100);
+
+	/* == red 140 - bt709 enc == */
+	out.a = 0xffff;
+	out.r = 0x8c8c;
+	out.g = 0x0;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 30 */
+	KUNIT_EXPECT_GT(test, out.r, 0x1D00);
+	KUNIT_EXPECT_LT(test, out.r, 0x1F00);
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x100);
+
+	/* V 87 */
+	KUNIT_EXPECT_GT(test, out.b, 0x5600);
+	KUNIT_EXPECT_LT(test, out.b, 0x5800);
+
+	/* == green 140 - bt709 enc == */
+	out.a = 0xffff;
+	out.r = 0x0;
+	out.g = 0x8c8c;
+	out.b = 0x0;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 30 */
+	KUNIT_EXPECT_GT(test, out.r, 0x6400);
+	KUNIT_EXPECT_LT(test, out.r, 0x6600);
+
+	/* U 0 */
+	KUNIT_EXPECT_LT(test, out.g, 0x100);
+
+	/* V 0 */
+	KUNIT_EXPECT_LT(test, out.b, 0x100);
+
+	/* == blue 140 - bt709 enc == */
+	out.a = 0xffff;
+	out.r = 0x0;
+	out.g = 0x0;
+	out.b = 0x8c8c;
+
+	apply_3x4_matrix(&out, &test_matrix_3x4_bt709_enc);
+
+	/* Y 30 */
+	KUNIT_EXPECT_GT(test, out.r, 0x900);
+	KUNIT_EXPECT_LT(test, out.r, 0xB00);
+
+	/* U 61 */
+	KUNIT_EXPECT_GT(test, out.g, 0x3C00);
+	KUNIT_EXPECT_LT(test, out.g, 0x3E00);
+
+	/* V 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),
 	{}
 };
 

drivers/gpu/drm/vkms/vkms_composer.c

@@ -128,7 +128,8 @@ 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)
+VISIBLE_IF_KUNIT void apply_3x4_matrix(struct pixel_argb_s32 *pixel,
+				       const struct drm_color_ctm_3x4 *matrix)
 {
 	s64 rf, gf, bf;
 	s64 r, g, b;
@@ -156,6 +157,7 @@ static void apply_3x4_matrix(struct pixel_argb_s32 *pixel, const struct drm_colo
 	pixel->g = drm_fixp2int_round(gf);
 	pixel->b = drm_fixp2int_round(bf);
 }
+EXPORT_SYMBOL_IF_KUNIT(apply_3x4_matrix);
 
 static void apply_colorop(struct pixel_argb_s32 *pixel, struct drm_colorop *colorop)
 {

drivers/gpu/drm/vkms/vkms_composer.h

@@ -22,6 +22,7 @@ u16 lerp_u16(u16 a, u16 b, s64 t);
 s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value);
 u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 channel_value,
 			       enum lut_channel channel);
+void apply_3x4_matrix(struct pixel_argb_s32 *pixel, const struct drm_color_ctm_3x4 *matrix);
 #endif
 
 #endif /* _VKMS_COMPOSER_H_ */