vkms: Change YUV helpers to support u16 inputs for conversion

Maíra Canal Fri, 27 Jun 2025 06:38:58 -0700

Hi Louis,

On 27/06/25 06:12, Louis Chauvet wrote:

Some YUV format uses 16 bit values, so change the helper function for
conversion to support those new formats.


Signed-off-by: Louis Chauvet <[email protected]>> ---
  drivers/gpu/drm/vkms/tests/vkms_format_test.c | 139 +++++++++++++-------------
  drivers/gpu/drm/vkms/vkms_formats.c           |  22 ++--
  drivers/gpu/drm/vkms/vkms_formats.h           |   4 +-
  3 files changed, 84 insertions(+), 81 deletions(-)


[...]

/*

- * vkms_format_test_yuv_u8_to_argb_u16 - Testing the conversion between YUV
+ * vkms_format_test_yuv_u16_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


s/argb_u16_from_yuv888/argb_u16_from_yuv161616

- * yuv_u8_to_argb_u16_cases) into ARGB colors.
+ * yuv_u16_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


From what I understand the input color now is 16 bits as well. Please,
update the comment.

Sorry, I missed those nits in the first review. Apart from that,

Reviewed-by: Maíra Canal <[email protected]>

Best Regards,
- Maíra

   * and output color is 16 bits.
   */
-static void vkms_format_test_yuv_u8_to_argb_u16(struct kunit *test)
+static void vkms_format_test_yuv_u16_to_argb_u16(struct kunit *test)
  {
-       const struct yuv_u8_to_argb_u16_case *param = test->param_value;
+       const struct yuv_u16_to_argb_u16_case *param = test->param_value;
        struct pixel_argb_u16 argb;

for (size_t i = 0; i < param->n_colors; i++) {

@@ -236,7 +236,8 @@ static void vkms_format_test_yuv_u8_to_argb_u16(struct 
kunit *test)
                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);

+               argb = argb_u16_from_yuv161616(&matrix, color->yuv.y, 
color->yuv.u,
+                                              color->yuv.v);

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",
@@ -253,19 +254,19 @@ static void vkms_format_test_yuv_u8_to_argb_u16(struct 
kunit *test)
        }
  }

-static void vkms_format_test_yuv_u8_to_argb_u16_case_desc(struct yuv_u8_to_argb_u16_case *t,

-                                                         char *desc)
+static void vkms_format_test_yuv_u16_to_argb_u16_case_desc(struct 
yuv_u16_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
+KUNIT_ARRAY_PARAM(yuv_u16_to_argb_u16, yuv_u16_to_argb_u16_cases,
+                 vkms_format_test_yuv_u16_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),
+       KUNIT_CASE_PARAM(vkms_format_test_yuv_u16_to_argb_u16, 
yuv_u16_to_argb_u16_gen_params),
        {}
  };

diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c

index 5b50e8622521..03eb73f4caef 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -269,16 +269,17 @@ static struct pixel_argb_u16 argb_u16_from_BGR565(const 
__le16 *pixel)
        return out_pixel;
  }

-VISIBLE_IF_KUNIT 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_yuv161616(const struct conversion_matrix 
*matrix,
+                                             u16 y, u16 channel_1, u16 
channel_2)
  {
        u16 r, g, b;
        s64 fp_y, fp_channel_1, fp_channel_2;
        s64 fp_r, fp_g, fp_b;

- fp_y = drm_int2fixp(((int)y - matrix->y_offset) * 257);

-       fp_channel_1 = drm_int2fixp(((int)channel_1 - 128) * 257);
-       fp_channel_2 = drm_int2fixp(((int)channel_2 - 128) * 257);
+       fp_y = drm_int2fixp((int)y - matrix->y_offset * 257);
+       fp_channel_1 = drm_int2fixp((int)channel_1 - 128 * 257);
+       fp_channel_2 = drm_int2fixp((int)channel_2 - 128 * 257);

fp_r = drm_fixp_mul(matrix->matrix[0][0], fp_y) +

               drm_fixp_mul(matrix->matrix[0][1], fp_channel_1) +
@@ -300,7 +301,7 @@ VISIBLE_IF_KUNIT struct pixel_argb_u16 
argb_u16_from_yuv888(u8 y, u8 channel_1,

return argb_u16_from_u16161616(0xffff, r, g, b);

  }
-EXPORT_SYMBOL_IF_KUNIT(argb_u16_from_yuv888);
+EXPORT_SYMBOL_IF_KUNIT(argb_u16_from_yuv161616);

/**

   * READ_LINE() - Generic generator for a read_line function which can be used 
for format with one
@@ -492,8 +493,8 @@ static void semi_planar_yuv_read_line(const struct 
vkms_plane_state *plane, int
        const struct conversion_matrix *conversion_matrix = 
&plane->conversion_matrix;

for (int i = 0; i < count; i++) {

-               *out_pixel = argb_u16_from_yuv888(y_plane[0], uv_plane[0], 
uv_plane[1],
-                                                 conversion_matrix);
+               *out_pixel = argb_u16_from_yuv161616(conversion_matrix, 
y_plane[0] * 257,
+                                                    uv_plane[0] * 257, 
uv_plane[1] * 257);
                out_pixel += 1;
                y_plane += step_y;
                if ((i + subsampling_offset + 1) % subsampling == 0)
@@ -537,8 +538,9 @@ static void planar_yuv_read_line(const struct 
vkms_plane_state *plane, int x_sta
        const struct conversion_matrix *conversion_matrix = 
&plane->conversion_matrix;

for (int i = 0; i < count; i++) {

-               *out_pixel = argb_u16_from_yuv888(*y_plane, *channel_1_plane, 
*channel_2_plane,
-                                                 conversion_matrix);
+               *out_pixel = argb_u16_from_yuv161616(conversion_matrix,
+                                                    *y_plane * 257, 
*channel_1_plane * 257,
+                                                    *channel_2_plane * 257);
                out_pixel += 1;
                y_plane += step_y;
                if ((i + subsampling_offset + 1) % subsampling == 0) {
diff --git a/drivers/gpu/drm/vkms/vkms_formats.h 
b/drivers/gpu/drm/vkms/vkms_formats.h
index b4fe62ab9c65..eeb208cdd6b1 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.h
+++ b/drivers/gpu/drm/vkms/vkms_formats.h
@@ -14,8 +14,8 @@ void get_conversion_matrix_to_argb_u16(u32 format, enum 
drm_color_encoding encod
                                       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);
+struct pixel_argb_u16 argb_u16_from_yuv161616(const struct conversion_matrix 
*matrix,
+                                             u16 y, u16 channel_1, u16 
channel_2);
  #endif

#endif /* _VKMS_FORMATS_H_ */

Re: [PATCH v5 6/8] drm/vkms: Change YUV helpers to support u16 inputs for conversion

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