On Mon, 26 Feb 2024 16:10:20 -0500
Harry Wentland <harry.wentland@xxxxxxx> wrote:
> Debugging LUT math is much easier when we can unit test
> it. Add kunit functionality to VKMS and add tests for
> - get_lut_index
> - lerp_u16
>
> v4:
> - Test the critical points of the lerp function (Pekka)
>
> v3:
> - Use include way of testing static functions (Arthur)
>
> Signed-off-by: Harry Wentland <harry.wentland@xxxxxxx>
> Cc: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
> ---
> drivers/gpu/drm/vkms/Kconfig | 5 +
> drivers/gpu/drm/vkms/tests/.kunitconfig | 4 +
> drivers/gpu/drm/vkms/tests/vkms_color_tests.c | 163 ++++++++++++++++++
> drivers/gpu/drm/vkms/vkms_composer.c | 8 +-
> 4 files changed, 178 insertions(+), 2 deletions(-)
> create mode 100644 drivers/gpu/drm/vkms/tests/.kunitconfig
> create mode 100644 drivers/gpu/drm/vkms/tests/vkms_color_tests.c
>
Hi Harry,
since fixed point math is hard, please allow me to nitpick so maybe
these patches could be landed ahead of time.
> diff --git a/drivers/gpu/drm/vkms/Kconfig b/drivers/gpu/drm/vkms/Kconfig
> index b9ecdebecb0b..c1f8b343ff0e 100644
> --- a/drivers/gpu/drm/vkms/Kconfig
> +++ b/drivers/gpu/drm/vkms/Kconfig
> @@ -13,3 +13,8 @@ config DRM_VKMS
> a VKMS.
>
> If M is selected the module will be called vkms.
> +
> +config DRM_VKMS_KUNIT_TESTS
> + tristate "Tests for VKMS" if !KUNIT_ALL_TESTS
> + depends on DRM_VKMS && KUNIT
> + default KUNIT_ALL_TESTS
> diff --git a/drivers/gpu/drm/vkms/tests/.kunitconfig b/drivers/gpu/drm/vkms/tests/.kunitconfig
> new file mode 100644
> index 000000000000..70e378228cbd
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/tests/.kunitconfig
> @@ -0,0 +1,4 @@
> +CONFIG_KUNIT=y
> +CONFIG_DRM=y
> +CONFIG_DRM_VKMS=y
> +CONFIG_DRM_VKMS_KUNIT_TESTS=y
> diff --git a/drivers/gpu/drm/vkms/tests/vkms_color_tests.c b/drivers/gpu/drm/vkms/tests/vkms_color_tests.c
> new file mode 100644
> index 000000000000..fc73e48aa57c
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/tests/vkms_color_tests.c
> @@ -0,0 +1,163 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +
> +#include <kunit/test.h>
> +
> +#include <drm/drm_fixed.h>
> +
> +#define TEST_LUT_SIZE 16
> +
> +static struct drm_color_lut test_linear_array[TEST_LUT_SIZE] = {
> + { 0x0, 0x0, 0x0, 0 },
> + { 0x1111, 0x1111, 0x1111, 0 },
> + { 0x2222, 0x2222, 0x2222, 0 },
> + { 0x3333, 0x3333, 0x3333, 0 },
> + { 0x4444, 0x4444, 0x4444, 0 },
> + { 0x5555, 0x5555, 0x5555, 0 },
> + { 0x6666, 0x6666, 0x6666, 0 },
> + { 0x7777, 0x7777, 0x7777, 0 },
> + { 0x8888, 0x8888, 0x8888, 0 },
> + { 0x9999, 0x9999, 0x9999, 0 },
> + { 0xaaaa, 0xaaaa, 0xaaaa, 0 },
> + { 0xbbbb, 0xbbbb, 0xbbbb, 0 },
> + { 0xcccc, 0xcccc, 0xcccc, 0 },
> + { 0xdddd, 0xdddd, 0xdddd, 0 },
> + { 0xeeee, 0xeeee, 0xeeee, 0 },
> + { 0xffff, 0xffff, 0xffff, 0 },
> +};
> +
> +const struct vkms_color_lut test_linear_lut = {
> + .base = test_linear_array,
> + .lut_length = TEST_LUT_SIZE,
> + .channel_value2index_ratio = 0xf000fll
Where does 0xf000f come from? Could it be computed from DRM_FIXED_ONE
and ARRAY_LENGTH()?
> +};
> +
> +
> +static void vkms_color_test_get_lut_index(struct kunit *test)
> +{
> + int i;
> +
> + KUNIT_EXPECT_EQ(test, drm_fixp2int(get_lut_index(&test_linear_lut, test_linear_array[0].red)), 0);
> +
> + for (i = 0; i < TEST_LUT_SIZE; i++)
> + KUNIT_EXPECT_EQ(test, drm_fixp2int_ceil(get_lut_index(&test_linear_lut, test_linear_array[i].red)), i);
Why this instead of
+ for (i = 0; i < TEST_LUT_SIZE; i++)
+ KUNIT_EXPECT_EQ(test, get_lut_index(&test_linear_lut, test_linear_array[i].red), drm_int2fixp(i));
and
+ for (i = 0; i < 0xffff; i++)
+ KUNIT_EXPECT_EQ(test, drm_fixp2int(get_lut_index(&test_linear_lut, i)), i / 0x1111);
?
I think your original form is leaving quite much room for error in
precision.
> +}
> +
> +static void vkms_color_test_lerp(struct kunit *test)
> +{
> + /*** half-way round down ***/
> + s64 t = 0x80000000 - 1;
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x10, t), 0x8);
> +
> + /* odd a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0x10, t), 0x8);
> +
> + /* odd b */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0xf, t), 0x8);
> +
> + /* b = a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x10, t), 0x10);
> +
> + /* b = a + 1 */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x11, t), 0x10);
> +
> +
> + /*** half-way round up ***/
> + t = 0x80000000;
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x10, t), 0x8);
> +
> + /* odd a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0x10, t), 0x9);
> +
> + /* odd b */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0xf, t), 0x8);
> +
> + /* b = a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x10, t), 0x10);
> +
> + /* b = a + 1 */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x11, t), 0x11);
> +
> + /*** t = 0.0 ***/
> + t = 0x0;
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x10, t), 0x0);
> +
> + /* odd a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0x10, t), 0x1);
> +
> + /* odd b */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0xf, t), 0x1);
> +
> + /* b = a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x10, t), 0x10);
> +
> + /* b = a + 1 */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x11, t), 0x10);
> +
> + /*** t = 1.0 ***/
> + t = 0x100000000;
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x10, t), 0x10);
> +
> + /* odd a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0x10, t), 0x10);
> +
> + /* odd b */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0xf, t), 0xf);
> +
> + /* b = a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x10, t), 0x10);
> +
> + /* b = a + 1 */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x11, t), 0x11);
> +
> +
> + /*** t = 0.0 + 1 ***/
> + t = 0x0 + 1;
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x10, t), 0x0);
> +
> + /* odd a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0x10, t), 0x1);
> +
> + /* odd b */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0xf, t), 0x1);
> +
> + /* b = a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x10, t), 0x10);
> +
> + /* b = a + 1 */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x11, t), 0x10);
> +
> + /*** t = 1.0 - 1 ***/
> + t = 0x100000000 - 1;
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x10, t), 0x10);
> +
> + /* odd a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0x10, t), 0x10);
> +
> + /* odd b */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x1, 0xf, t), 0xf);
> +
> + /* b = a */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x10, t), 0x10);
> +
> + /* b = a + 1 */
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x10, 0x11, t), 0x11);
> +
> +
> + /*** t chosen to verify the flipping point of result a (or b) to a+1 (or b-1) ***/
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x1, 0x80000000 - 1), 0x0);
> + KUNIT_EXPECT_EQ(test, lerp_u16(0x0, 0x1, 0x80000000), 0x1);
What about b = 0xfffd also? The smaller number in b, and especially in
b - a, the more precision error the rounding will forgive.
> +}
> +
> +static struct kunit_case vkms_color_test_cases[] = {
> + KUNIT_CASE(vkms_color_test_get_lut_index),
> + KUNIT_CASE(vkms_color_test_lerp),
> + {}
> +};
> +
> +static struct kunit_suite vkms_color_test_suite = {
> + .name = "vkms-color",
> + .test_cases = vkms_color_test_cases,
> +};
> +kunit_test_suite(vkms_color_test_suite);
> +
> +MODULE_LICENSE("GPL");
> \ No newline at end of file
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index e70cd473e3be..d178f2a400f6 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -91,7 +91,7 @@ static void fill_background(const struct pixel_argb_u16 *background_color,
> }
>
> // lerp(a, b, t) = a + (b - a) * t
> -static u16 lerp_u16(u16 a, u16 b, s64 t)
> +u16 lerp_u16(u16 a, u16 b, s64 t)
> {
> s64 a_fp = drm_int2fixp(a);
> s64 b_fp = drm_int2fixp(b);
> @@ -101,7 +101,7 @@ static u16 lerp_u16(u16 a, u16 b, s64 t)
> return drm_fixp2int_round(a_fp + delta);
Given the past, I guess it wouldn't hurt if all drm fixp functions had
a few tests of their own.
Thanks,
pq
> }
>
> -static s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value)
> +s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value)
> {
> s64 color_channel_fp = drm_int2fixp(channel_value);
>
> @@ -429,3 +429,7 @@ int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
>
> return ret;
> }
> +
> +#ifdef CONFIG_DRM_VKMS_KUNIT_TESTS
> +#include "tests/vkms_color_tests.c"
> +#endif
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