[PATCH v18 6/8] drm/vkms: Create KUnit tests for YUV conversions

From: Louis Chauvet
Date: Tue Apr 15 2025 - 09:58:03 EST

From: Arthur Grillo <arthurgrillo@xxxxxxxxxx>

Create KUnit tests to test the conversion between YUV and RGB. Test each
conversion and range combination with some common colors.

The code used to compute the expected result can be found in comment.

[Louis Chauvet:
- fix minor formating issues (whitespace, double line)
- change expected alpha from 0x0000 to 0xffff
- adapt to the new get_conversion_matrix usage
- apply the changes from Arthur
- move struct pixel_yuv_u8 to the test itself]

Signed-off-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
Acked-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx>
Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
---
drivers/gpu/drm/vkms/tests/Makefile | 1 +
drivers/gpu/drm/vkms/tests/vkms_format_test.c | 280 ++++++++++++++++++++++++++
drivers/gpu/drm/vkms/vkms_formats.c | 7 +-
drivers/gpu/drm/vkms/vkms_formats.h | 5 +
4 files changed, 291 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vkms/tests/Makefile b/drivers/gpu/drm/vkms/tests/Makefile
index 9ded37b67a46..0ee077942ae2 100644
--- a/drivers/gpu/drm/vkms/tests/Makefile
+++ b/drivers/gpu/drm/vkms/tests/Makefile
@@ -1,3 +1,4 @@
# SPDX-License-Identifier: GPL-2.0-only

obj-$(CONFIG_DRM_VKMS_KUNIT_TEST) += vkms_config_test.o
+obj-$(CONFIG_DRM_VKMS_KUNIT_TESTS) += vkms_format_test.o
diff --git a/drivers/gpu/drm/vkms/tests/vkms_format_test.c b/drivers/gpu/drm/vkms/tests/vkms_format_test.c
new file mode 100644
index 000000000000..2e1daef94831
--- /dev/null
+++ b/drivers/gpu/drm/vkms/tests/vkms_format_test.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <kunit/test.h>
+
+#include <drm/drm_fixed.h>
+#include <drm/drm_fourcc.h>
+
+#include "../../drm_crtc_internal.h"
+
+#include "../vkms_formats.h"
+
+#define TEST_BUFF_SIZE 50
+
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
+
+/**
+ * struct pixel_yuv_u8 - Internal representation of a pixel color.
+ * @y: Luma value, stored in 8 bits, without padding, using
+ * machine endianness
+ * @u: Blue difference chroma value, stored in 8 bits, without padding, using
+ * machine endianness
+ * @v: Red difference chroma value, stored in 8 bits, without padding, using
+ * machine endianness
+ */
+struct pixel_yuv_u8 {
+ u8 y, u, v;
+};
+
+/*
+ * struct yuv_u8_to_argb_u16_case - Reference values to test the color
+ * conversions in VKMS between YUV to ARGB
+ *
+ * @encoding: Encoding used to convert RGB to YUV
+ * @range: Range used to convert RGB to YUV
+ * @n_colors: Count of test colors in this case
+ * @format_pair.name: Name used for this color conversion, used to
+ * clarify the test results
+ * @format_pair.rgb: RGB color tested
+ * @format_pair.yuv: Same color as @format_pair.rgb, but converted to
+ * YUV using @encoding and @range.
+ */
+struct yuv_u8_to_argb_u16_case {
+ enum drm_color_encoding encoding;
+ enum drm_color_range range;
+ size_t n_colors;
+ struct format_pair {
+ char *name;
+ struct pixel_yuv_u8 yuv;
+ struct pixel_argb_u16 argb;
+ } colors[TEST_BUFF_SIZE];
+};
+
+/*
+ * The YUV color representation were acquired via the colour python framework.
+ * Below are the function calls used for generating each case.
+ *
+ * For more information got to the docs:
+ * https://colour.readthedocs.io/en/master/generated/colour.RGB_to_YCbCr.html
+ */
+static struct yuv_u8_to_argb_u16_case yuv_u8_to_argb_u16_cases[] = {
+ /*
+ * colour.RGB_to_YCbCr(<rgb color in 16 bit form>,
+ * K=colour.WEIGHTS_YCBCR["ITU-R BT.601"],
+ * in_bits = 16,
+ * in_legal = False,
+ * in_int = True,
+ * out_bits = 8,
+ * out_legal = False,
+ * out_int = True)
+ *
+ * Tests cases for color conversion generated by converting RGB
+ * values to YUV BT601 full range using the ITU-R BT.601 weights.
+ */
+ {
+ .encoding = DRM_COLOR_YCBCR_BT601,
+ .range = DRM_COLOR_YCBCR_FULL_RANGE,
+ .n_colors = 6,
+ .colors = {
+ { "white", { 0xff, 0x80, 0x80 }, { 0xffff, 0xffff, 0xffff, 0xffff }},
+ { "gray", { 0x80, 0x80, 0x80 }, { 0xffff, 0x8080, 0x8080, 0x8080 }},
+ { "black", { 0x00, 0x80, 0x80 }, { 0xffff, 0x0000, 0x0000, 0x0000 }},
+ { "red", { 0x4c, 0x55, 0xff }, { 0xffff, 0xffff, 0x0000, 0x0000 }},
+ { "green", { 0x96, 0x2c, 0x15 }, { 0xffff, 0x0000, 0xffff, 0x0000 }},
+ { "blue", { 0x1d, 0xff, 0x6b }, { 0xffff, 0x0000, 0x0000, 0xffff }},
+ },
+ },
+ /*
+ * colour.RGB_to_YCbCr(<rgb color in 16 bit form>,
+ * K=colour.WEIGHTS_YCBCR["ITU-R BT.601"],
+ * in_bits = 16,
+ * in_legal = False,
+ * in_int = True,
+ * out_bits = 8,
+ * out_legal = True,
+ * out_int = True)
+ * Tests cases for color conversion generated by converting RGB
+ * values to YUV BT601 limited range using the ITU-R BT.601 weights.
+ */
+ {
+ .encoding = DRM_COLOR_YCBCR_BT601,
+ .range = DRM_COLOR_YCBCR_LIMITED_RANGE,
+ .n_colors = 6,
+ .colors = {
+ { "white", { 0xeb, 0x80, 0x80 }, { 0xffff, 0xffff, 0xffff, 0xffff }},
+ { "gray", { 0x7e, 0x80, 0x80 }, { 0xffff, 0x8080, 0x8080, 0x8080 }},
+ { "black", { 0x10, 0x80, 0x80 }, { 0xffff, 0x0000, 0x0000, 0x0000 }},
+ { "red", { 0x51, 0x5a, 0xf0 }, { 0xffff, 0xffff, 0x0000, 0x0000 }},
+ { "green", { 0x91, 0x36, 0x22 }, { 0xffff, 0x0000, 0xffff, 0x0000 }},
+ { "blue", { 0x29, 0xf0, 0x6e }, { 0xffff, 0x0000, 0x0000, 0xffff }},
+ },
+ },
+ /*
+ * colour.RGB_to_YCbCr(<rgb color in 16 bit form>,
+ * K=colour.WEIGHTS_YCBCR["ITU-R BT.709"],
+ * in_bits = 16,
+ * in_legal = False,
+ * in_int = True,
+ * out_bits = 8,
+ * out_legal = False,
+ * out_int = True)
+ * Tests cases for color conversion generated by converting RGB
+ * values to YUV BT709 full range using the ITU-R BT.709 weights.
+ */
+ {
+ .encoding = DRM_COLOR_YCBCR_BT709,
+ .range = DRM_COLOR_YCBCR_FULL_RANGE,
+ .n_colors = 6,
+ .colors = {
+ { "white", { 0xff, 0x80, 0x80 }, { 0xffff, 0xffff, 0xffff, 0xffff }},
+ { "gray", { 0x80, 0x80, 0x80 }, { 0xffff, 0x8080, 0x8080, 0x8080 }},
+ { "black", { 0x00, 0x80, 0x80 }, { 0xffff, 0x0000, 0x0000, 0x0000 }},
+ { "red", { 0x36, 0x63, 0xff }, { 0xffff, 0xffff, 0x0000, 0x0000 }},
+ { "green", { 0xb6, 0x1e, 0x0c }, { 0xffff, 0x0000, 0xffff, 0x0000 }},
+ { "blue", { 0x12, 0xff, 0x74 }, { 0xffff, 0x0000, 0x0000, 0xffff }},
+ },
+ },
+ /*
+ * colour.RGB_to_YCbCr(<rgb color in 16 bit form>,
+ * K=colour.WEIGHTS_YCBCR["ITU-R BT.709"],
+ * in_bits = 16,
+ * int_legal = False,
+ * in_int = True,
+ * out_bits = 8,
+ * out_legal = True,
+ * out_int = True)
+ * Tests cases for color conversion generated by converting RGB
+ * values to YUV BT709 limited range using the ITU-R BT.709 weights.
+ */
+ {
+ .encoding = DRM_COLOR_YCBCR_BT709,
+ .range = DRM_COLOR_YCBCR_LIMITED_RANGE,
+ .n_colors = 6,
+ .colors = {
+ { "white", { 0xeb, 0x80, 0x80 }, { 0xffff, 0xffff, 0xffff, 0xffff }},
+ { "gray", { 0x7e, 0x80, 0x80 }, { 0xffff, 0x8080, 0x8080, 0x8080 }},
+ { "black", { 0x10, 0x80, 0x80 }, { 0xffff, 0x0000, 0x0000, 0x0000 }},
+ { "red", { 0x3f, 0x66, 0xf0 }, { 0xffff, 0xffff, 0x0000, 0x0000 }},
+ { "green", { 0xad, 0x2a, 0x1a }, { 0xffff, 0x0000, 0xffff, 0x0000 }},
+ { "blue", { 0x20, 0xf0, 0x76 }, { 0xffff, 0x0000, 0x0000, 0xffff }},
+ },
+ },
+ /*
+ * colour.RGB_to_YCbCr(<rgb color in 16 bit form>,
+ * K=colour.WEIGHTS_YCBCR["ITU-R BT.2020"],
+ * in_bits = 16,
+ * in_legal = False,
+ * in_int = True,
+ * out_bits = 8,
+ * out_legal = False,
+ * out_int = True)
+ * Tests cases for color conversion generated by converting RGB
+ * values to YUV BT2020 full range using the ITU-R BT.2020 weights.
+ */
+ {
+ .encoding = DRM_COLOR_YCBCR_BT2020,
+ .range = DRM_COLOR_YCBCR_FULL_RANGE,
+ .n_colors = 6,
+ .colors = {
+ { "white", { 0xff, 0x80, 0x80 }, { 0xffff, 0xffff, 0xffff, 0xffff }},
+ { "gray", { 0x80, 0x80, 0x80 }, { 0xffff, 0x8080, 0x8080, 0x8080 }},
+ { "black", { 0x00, 0x80, 0x80 }, { 0xffff, 0x0000, 0x0000, 0x0000 }},
+ { "red", { 0x43, 0x5c, 0xff }, { 0xffff, 0xffff, 0x0000, 0x0000 }},
+ { "green", { 0xad, 0x24, 0x0b }, { 0xffff, 0x0000, 0xffff, 0x0000 }},
+ { "blue", { 0x0f, 0xff, 0x76 }, { 0xffff, 0x0000, 0x0000, 0xffff }},
+ },
+ },
+ /*
+ * colour.RGB_to_YCbCr(<rgb color in 16 bit form>,
+ * K=colour.WEIGHTS_YCBCR["ITU-R BT.2020"],
+ * in_bits = 16,
+ * in_legal = False,
+ * in_int = True,
+ * out_bits = 8,
+ * out_legal = True,
+ * out_int = True)
+ * Tests cases for color conversion generated by converting RGB
+ * values to YUV BT2020 limited range using the ITU-R BT.2020 weights.
+ */
+ {
+ .encoding = DRM_COLOR_YCBCR_BT2020,
+ .range = DRM_COLOR_YCBCR_LIMITED_RANGE,
+ .n_colors = 6,
+ .colors = {
+ { "white", { 0xeb, 0x80, 0x80 }, { 0xffff, 0xffff, 0xffff, 0xffff }},
+ { "gray", { 0x7e, 0x80, 0x80 }, { 0xffff, 0x8080, 0x8080, 0x8080 }},
+ { "black", { 0x10, 0x80, 0x80 }, { 0xffff, 0x0000, 0x0000, 0x0000 }},
+ { "red", { 0x4a, 0x61, 0xf0 }, { 0xffff, 0xffff, 0x0000, 0x0000 }},
+ { "green", { 0xa4, 0x2f, 0x19 }, { 0xffff, 0x0000, 0xffff, 0x0000 }},
+ { "blue", { 0x1d, 0xf0, 0x77 }, { 0xffff, 0x0000, 0x0000, 0xffff }},
+ },
+ },
+};
+
+/*
+ * vkms_format_test_yuv_u8_to_argb_u16 - Testing the conversion between YUV
+ * colors to ARGB colors in VKMS
+ *
+ * This test will use the functions get_conversion_matrix_to_argb_u16 and
+ * argb_u16_from_yuv888 to convert YUV colors (stored in
+ * yuv_u8_to_argb_u16_cases) into ARGB colors.
+ *
+ * The conversion between YUV and RGB is not totally reversible, so there may be
+ * some difference between the expected value and the result.
+ * In addition, there may be some rounding error as the input color is 8 bits
+ * and output color is 16 bits.
+ */
+static void vkms_format_test_yuv_u8_to_argb_u16(struct kunit *test)
+{
+ const struct yuv_u8_to_argb_u16_case *param = test->param_value;
+ struct pixel_argb_u16 argb;
+
+ for (size_t i = 0; i < param->n_colors; i++) {
+ const struct format_pair *color = &param->colors[i];
+ struct conversion_matrix matrix;
+
+ get_conversion_matrix_to_argb_u16
+ (DRM_FORMAT_NV12, param->encoding, param->range, &matrix);
+
+ argb = argb_u16_from_yuv888(color->yuv.y, color->yuv.u, color->yuv.v, &matrix);
+
+ KUNIT_EXPECT_LE_MSG(test, abs_diff(argb.a, color->argb.a), 0x1ff,
+ "On the A channel of the color %s expected 0x%04x, got 0x%04x",
+ color->name, color->argb.a, argb.a);
+ KUNIT_EXPECT_LE_MSG(test, abs_diff(argb.r, color->argb.r), 0x1ff,
+ "On the R channel of the color %s expected 0x%04x, got 0x%04x",
+ color->name, color->argb.r, argb.r);
+ KUNIT_EXPECT_LE_MSG(test, abs_diff(argb.g, color->argb.g), 0x1ff,
+ "On the G channel of the color %s expected 0x%04x, got 0x%04x",
+ color->name, color->argb.g, argb.g);
+ KUNIT_EXPECT_LE_MSG(test, abs_diff(argb.b, color->argb.b), 0x1ff,
+ "On the B channel of the color %s expected 0x%04x, got 0x%04x",
+ color->name, color->argb.b, argb.b);
+ }
+}
+
+static void vkms_format_test_yuv_u8_to_argb_u16_case_desc(struct yuv_u8_to_argb_u16_case *t,
+ char *desc)
+{
+ snprintf(desc, KUNIT_PARAM_DESC_SIZE, "%s - %s",
+ drm_get_color_encoding_name(t->encoding), drm_get_color_range_name(t->range));
+}
+
+KUNIT_ARRAY_PARAM(yuv_u8_to_argb_u16, yuv_u8_to_argb_u16_cases,
+ vkms_format_test_yuv_u8_to_argb_u16_case_desc
+);
+
+static struct kunit_case vkms_format_test_cases[] = {
+ KUNIT_CASE_PARAM(vkms_format_test_yuv_u8_to_argb_u16, yuv_u8_to_argb_u16_gen_params),
+ {}
+};
+
+static struct kunit_suite vkms_format_test_suite = {
+ .name = "vkms-format",
+ .test_cases = vkms_format_test_cases,
+};
+
+kunit_test_suite(vkms_format_test_suite);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Kunit test for vkms format conversion");
diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
index 8f7a5d54a076..9972780f3fa9 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -7,6 +7,8 @@
#include <drm/drm_rect.h>
#include <drm/drm_fixed.h>

+#include <kunit/visibility.h>
+
#include "vkms_formats.h"

/**
@@ -247,8 +249,8 @@ static struct pixel_argb_u16 argb_u16_from_RGB565(const __le16 *pixel)
return out_pixel;
}

-static struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1, u8 channel_2,
- const struct conversion_matrix *matrix)
+VISIBLE_IF_KUNIT struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1, u8 channel_2,
+ const struct conversion_matrix *matrix)
{
u16 r, g, b;
s64 fp_y, fp_channel_1, fp_channel_2;
@@ -278,6 +280,7 @@ static struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1, u8 channel

return argb_u16_from_u16161616(0xffff, r, g, b);
}
+EXPORT_SYMBOL_IF_KUNIT(argb_u16_from_yuv888);

/*
* The following functions are read_line function for each pixel format supported by VKMS.
diff --git a/drivers/gpu/drm/vkms/vkms_formats.h b/drivers/gpu/drm/vkms/vkms_formats.h
index d583855cb320..b4fe62ab9c65 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.h
+++ b/drivers/gpu/drm/vkms/vkms_formats.h
@@ -13,4 +13,9 @@ void get_conversion_matrix_to_argb_u16(u32 format, enum drm_color_encoding encod
enum drm_color_range range,
struct conversion_matrix *matrix);

+#if IS_ENABLED(CONFIG_KUNIT)
+struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1, u8 channel_2,
+ const struct conversion_matrix *matrix);
+#endif
+
#endif /* _VKMS_FORMATS_H_ */

--
2.49.0