On Mon, 26 Feb 2024 16:10:39 -0500
Harry Wentland <harry.wentland@xxxxxxx> wrote:
> 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.
>
> v4:
> - Comment on origin of bt709_enc matrix (Pekka)
> - Use full opaque alpha (Pekka)
> - Add additional check for Y < 0xffff (Pekka)
> - Remove unused code (Pekka)
> - Rename red, green, blue to Y, U, V where applicable
>
> Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx>
> ---
> drivers/gpu/drm/vkms/tests/vkms_color_tests.c | 251 ++++++++++++++++++
> drivers/gpu/drm/vkms/vkms_composer.c | 2 +-
> 2 files changed, 252 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vkms/tests/vkms_color_tests.c b/drivers/gpu/drm/vkms/tests/vkms_color_tests.c
> index e6ac01dee830..83d07f7bae37 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
>
> @@ -181,11 +182,261 @@ 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
These are supposed to be sign-magnitude, not fixed-point, to my
understanding. It just happens that these specific values have the same
bit pattern in both representations.
> +} };
> +
> +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 = 0x7fff;
> + ref.g = 0x3fff;
> + ref.b = 0x3fff;
> +
> + 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.
Shouldn't that be sign-magnitude, not fixed point?
I was hoping to get a reference to a spec like BT.709 and a formula for
getting the blow out of it. IGT can change over time, and I don't know
where IGT for that matrix from.
But ok, this is a test with an arbitrary matrix, not necessarily the
BT.709 matrix specifically.
Btw. which BT.709 matrix is this? YUV->RGB, RGB->XYZ, or the inverse of
one of those? Limited or full quantization range?
Judging by the tests, I guess RGB->YUV full range.
> + */
> +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);
For all of these U/V too, you may want to enforce a range. The value
must be approximately 0x100. Something like 0x17 would very wrong.
Hmm, wait...
Neutral color should have U and V neutral, that is, zero, right? So
what is zero in this integer representation?
You don't seem to be testing negative U or V...
Thanks,
pq
> +
> + /* 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),
> {}
> };
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index 8bbfce651526..2c5715242f91 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;
>
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