Re: [PATCH v2 01/13] drm/colorop: Add DRM_COLOROP_FIXED_MATRIX

Melissa Wen
2026-04-21T13:11:03Z

On 08/04/2026 02:15, Chaitanya Kumar Borah wrote:
> Introduce DRM_COLOROP_FIXED_MATRIX, a new colorop type representing a
> hardware that performs a fixed matrix operation.
>
> Unlike CTM-based colorops, this block does not expose programmable
> coefficients. Instead, userspace selects one of the predefined
> hardware modes via a new FIXED_MATRIX_TYPE enum property. Supported modes
> include common YCbCr->RGB and RGB709->RGB2020 conversions.
>
> v2:
> - Naming changes (Pekka)
>
> Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
> ---
> drivers/gpu/drm/drm_atomic.c | 4 ++
> drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
> drivers/gpu/drm/drm_colorop.c | 107 ++++++++++++++++++++++++++++++
> include/drm/drm_colorop.h | 84 +++++++++++++++++++++++
> include/uapi/drm/drm_mode.h | 12 ++++
> 5 files changed, 211 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 41c57063f3b4..16a2183b11bf 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -845,6 +845,10 @@ static void drm_atomic_colorop_print_state(struct drm_printer *p,
> drm_get_colorop_lut3d_interpolation_name(colorop->lut3d_interpolation));
> drm_printf(p, "\tdata blob id=%d\n", state->data ? state->data->base.id : 0);
> break;
> + case DRM_COLOROP_FIXED_MATRIX:
> + drm_printf(p, "\tfixed_matrix_type=%s\n",
> + drm_get_colorop_fixed_matrix_type_name(state->fixed_matrix_type));
> + break;
> default:
> break;
> }
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index 5bd5bf6661df..d69406b08a0f 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -761,6 +761,8 @@ static int drm_atomic_colorop_set_property(struct drm_colorop *colorop,
> } else if (property == colorop->data_property) {
> return drm_atomic_color_set_data_property(colorop, state,
> property, val);
> + } else if (property == colorop->fixed_matrix_type_property) {
> + state->fixed_matrix_type = val;
> } else {
> drm_dbg_atomic(colorop->dev,
> "[COLOROP:%d:%d] unknown property [PROP:%d:%s]\n",
> @@ -793,6 +795,8 @@ drm_atomic_colorop_get_property(struct drm_colorop *colorop,
> *val = colorop->lut3d_interpolation;
> else if (property == colorop->data_property)
> *val = (state->data) ? state->data->base.id : 0;
> + else if (property == colorop->fixed_matrix_type_property)
> + *val = state->fixed_matrix_type;
> else
> return -EINVAL;
>
> diff --git a/drivers/gpu/drm/drm_colorop.c b/drivers/gpu/drm/drm_colorop.c
> index 566816e3c6f0..dd385e8dacbe 100644
> --- a/drivers/gpu/drm/drm_colorop.c
> +++ b/drivers/gpu/drm/drm_colorop.c
> @@ -68,6 +68,7 @@ static const struct drm_prop_enum_list drm_colorop_type_enum_list[] = {
> { DRM_COLOROP_CTM_3X4, "3x4 Matrix"},
> { DRM_COLOROP_MULTIPLIER, "Multiplier"},
> { DRM_COLOROP_3D_LUT, "3D LUT"},
> + { DRM_COLOROP_FIXED_MATRIX, "Fixed Matrix"},
> };
>
> static const char * const colorop_curve_1d_type_names[] = {
> @@ -90,6 +91,14 @@ static const struct drm_prop_enum_list drm_colorop_lut3d_interpolation_list[] =
> { DRM_COLOROP_LUT3D_INTERPOLATION_TETRAHEDRAL, "Tetrahedral" },
> };
>
> +static const char * const colorop_fixed_matrix_type_names[] = {
> + [DRM_COLOROP_FM_YCBCR601_FULL_RGB] = "YCbCr 601 Full to RGB",
> + [DRM_COLOROP_FM_YCBCR709_FULL_RGB] = "YCbCr 709 Full to RGB",
> + [DRM_COLOROP_FM_YCBCR2020_FULL_RGB_NC] = "YCbCr 2020 Full to RGB NC",
> + [DRM_COLOROP_FM_YCBCR_LIMITED_FULL] = "YCbCr limited to full",
> + [DRM_COLOROP_FM_RGB709_RGB2020] = "RGB709 to RGB2020",
> +};
> +
> /* Init Helpers */
>
> static int drm_plane_colorop_init(struct drm_device *dev, struct drm_colorop *colorop,
> @@ -455,6 +464,81 @@ int drm_plane_colorop_3dlut_init(struct drm_device *dev, struct drm_colorop *col
> }
> EXPORT_SYMBOL(drm_plane_colorop_3dlut_init);
>
> +/**
> + * drm_plane_colorop_fixed_matrix_init - Initialize a DRM_COLOROP_FIXED_MATRIX
> + *
> + * @dev: DRM device
> + * @colorop: The drm_colorop object to initialize
> + * @plane: The associated drm_plane
> + * @funcs: control functions for the new colorop
> + * @supported_fm: A bitfield of supported drm_colorop_fixed_matrix_type enum values,
> + * created using BIT(fixed_matrix_type) and combined with the OR '|'
> + * operator.
> + * @flags: bitmask of misc, see DRM_COLOROP_FLAG_* defines.
> + * @return zero on success, -E value on failure
> + */
> +int drm_plane_colorop_fixed_matrix_init(struct drm_device *dev, struct drm_colorop *colorop,
> + struct drm_plane *plane,
> + const struct drm_colorop_funcs *funcs,
> + u64 supported_fm, uint32_t flags)
> +{
> + struct drm_prop_enum_list enum_list[DRM_COLOROP_FM_COUNT];
> + int i, len;
> +
> + struct drm_property *prop;
> + int ret;
> +
> + if (!supported_fm) {
> + drm_err(dev,
> + "No supported FM type op for new Fixed Matrix colorop on [PLANE:%d:%s]\n",
> + plane->base.id, plane->name);
> + return -EINVAL;
> + }
> +
> + if ((supported_fm & -BIT(DRM_COLOROP_FM_COUNT)) != 0) {
> + drm_err(dev, "Unknown Fixed Matrix provided on [PLANE:%d:%s]\n",
> + plane->base.id, plane->name);
> + return -EINVAL;
> + }
> +
> + ret = drm_plane_colorop_init(dev, colorop, plane, funcs, DRM_COLOROP_FIXED_MATRIX, flags);
> + if (ret)
> + return ret;
> +
> + len = 0;
> + for (i = 0; i < DRM_COLOROP_FM_COUNT; i++) {
> + if ((supported_fm & BIT(i)) == 0)
> + continue;
> +
> + enum_list[len].type = i;
> + enum_list[len].name = colorop_fixed_matrix_type_names[i];
> + len++;
> + }
> +
> + if (WARN_ON(len <= 0))
> + return -EINVAL;
> +
> + prop = drm_property_create_enum(dev, DRM_MODE_PROP_ATOMIC, "FIXED_MATRIX_TYPE",
> + enum_list, len);
> +
> + if (!prop)
> + return -ENOMEM;
> +
> + colorop->fixed_matrix_type_property = prop;
> + /*
> + * Default to the first supported CSC mode as provided by the driver.
> + * Intuitively this should be something that keeps the colorop in pixel bypass
> + * mode but that is already handled via the standard colorop bypass
> + * property.
> + */
> + drm_object_attach_property(&colorop->base, colorop->fixed_matrix_type_property,
> + enum_list[0].type);
> + drm_colorop_reset(colorop);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_plane_colorop_fixed_matrix_init);
> +
> static void __drm_atomic_helper_colorop_duplicate_state(struct drm_colorop *colorop,
> struct drm_colorop_state *state)
> {
> @@ -521,6 +605,13 @@ static void __drm_colorop_state_reset(struct drm_colorop_state *colorop_state,
> &val);
> colorop_state->curve_1d_type = val;
> }
> +
> + if (colorop->fixed_matrix_type_property) {
> + drm_object_property_get_default_value(&colorop->base,
> + colorop->fixed_matrix_type_property,
> + &val);
> + colorop_state->fixed_matrix_type = val;
> + }
> }
>
> /**
> @@ -561,6 +652,7 @@ static const char * const colorop_type_name[] = {
> [DRM_COLOROP_CTM_3X4] = "3x4 Matrix",
> [DRM_COLOROP_MULTIPLIER] = "Multiplier",
> [DRM_COLOROP_3D_LUT] = "3D LUT",
> + [DRM_COLOROP_FIXED_MATRIX] = "Fixed Matrix",
> };
>
> static const char * const colorop_lu3d_interpolation_name[] = {
> @@ -617,6 +709,21 @@ const char *drm_get_colorop_lut3d_interpolation_name(enum drm_colorop_lut3d_inte
> return colorop_lu3d_interpolation_name[type];
> }
>
> +/**
> + * drm_get_colorop_fixed_matrix_type_name: return a string for fixed matrix type
> + * @type: fixed matrix type to compute name of
> + *
> + * In contrast to the other drm_get_*_name functions this one here returns a
> + * const pointer and hence is threadsafe.
> + */
> +const char *drm_get_colorop_fixed_matrix_type_name(enum drm_colorop_fixed_matrix_type type)
> +{
> + if (WARN_ON(type >= ARRAY_SIZE(colorop_fixed_matrix_type_names)))
> + return "unknown";
> +
> + return colorop_fixed_matrix_type_names[type];
> +}
> +
> /**
> * drm_colorop_set_next_property - sets the next pointer
> * @colorop: drm colorop
> diff --git a/include/drm/drm_colorop.h b/include/drm/drm_colorop.h
> index bd082854ca74..c13b4b045fff 100644
> --- a/include/drm/drm_colorop.h
> +++ b/include/drm/drm_colorop.h
> @@ -134,6 +134,71 @@ enum drm_colorop_curve_1d_type {
> DRM_COLOROP_1D_CURVE_COUNT
> };
>
> +/**
> + * enum drm_colorop_fixed_matrix_type - type of Fixed Matrix
> + *
> + * Describes a Fixed Matrix operation to be applied by the DRM_COLOROP_FIXED_MATRIX
> + */
> +enum drm_colorop_fixed_matrix_type {
> + /**
> + * @DRM_COLOROP_FM_YCBCR601_FULL_RGB:
> + *
> + * enum string "YCbCr 601 Full to RGB"
> + *
> + * This selects the matrix that converts full range YCbCr into RGB
> + * according to the BT.601 coefficients.
> + */
> + DRM_COLOROP_FM_YCBCR601_FULL_RGB,
> +
> + /**
> + * @DRM_COLOROP_FM_YCBCR709_FULL_RGB:
> + *
> + * enum string "YCbCr 709 Full to RGB"
> + *
> + * This selects the matrix that converts full range YCbCr into RGB
> + * according to the BT.709 coefficients.
> + */
> + DRM_COLOROP_FM_YCBCR709_FULL_RGB,
> +
> + /**
> + * @DRM_COLOROP_FM_YCBCR2020_NC_FULL_RGB:
> + *
> + * enum string "YCbCr 2020 Full to RGB NC"
Nit: I think you mean "YCbCr 2020 NC Full to RGB"?
> + *
> + * This selects the matrix that converts full range YCbCr into RGB
> + * according to the BT.2020 non-constant luminance coefficients.
> + */
> + DRM_COLOROP_FM_YCBCR2020_FULL_RGB_NC,
... and here ^ DRM_COLOROP_FM_YCBCR_NC_FULL_RGB
> +
> + /**
> + * @DRM_COLOROP_FM_YCBCR_LIMITED_FULL:
> + *
> + * enum string "YCbCr limited to full"
> + *
> + * This selects the matrix that converts limited range YCbCr into
> + * full range YCbCr. Though not strictly a matrix operation but
> + * can be represented as one.
> + */
> + DRM_COLOROP_FM_YCBCR_LIMITED_FULL,
I didn't full understand how this is going to work.
Looks like it's merging two properties (COLOR_ENCODING and COLOR_RANGE)
in a single colorop.
But we can only select one enum value. So how to communicate, for
example, a "YCbCr 709 Limited to RGB" conversion?
The driver will have to define a coloro pipeline with two fixed matrix
colorop in a row, one with only "Limited to Full" and another with
"YCbCr Full to RGB" ?

Melissa
> +
> + /**
> + * @DRM_COLOROP_FM_RGB709_RGB2020:
> + *
> + * enum string "RGB709 to RGB2020"
> + *
> + * Selects the fixed-function CSC preset that converts RGB
> + * (BT.709) colorimetry to RGB (BT.2020).
> + */
> + DRM_COLOROP_FM_RGB709_RGB2020,
> +
> + /**
> + * @DRM_COLOROP_FM_COUNT:
> + *
> + * enum value denoting the size of the enum
> + */
> + DRM_COLOROP_FM_COUNT
> +};
> +
> /**
> * struct drm_colorop_state - mutable colorop state
> */
> @@ -183,6 +248,13 @@ struct drm_colorop_state {
> */
> struct drm_property_blob *data;
>
> + /**
> + * @fixed_matrix_type:
> + *
> + * Type of Fixed Matrix operation.
> + */
> + enum drm_colorop_fixed_matrix_type fixed_matrix_type;
> +
> /** @state: backpointer to global drm_atomic_state */
> struct drm_atomic_state *state;
> };
> @@ -368,6 +440,13 @@ struct drm_colorop {
> */
> struct drm_property *data_property;
>
> + /**
> + * @fixed_matrix_type_property:
> + *
> + * Sub-type for DRM_COLOROP_FIXED_MATRIX type.
> + */
> + struct drm_property *fixed_matrix_type_property;
> +
> /**
> * @next_property:
> *
> @@ -424,6 +503,10 @@ int drm_plane_colorop_3dlut_init(struct drm_device *dev, struct drm_colorop *col
> uint32_t lut_size,
> enum drm_colorop_lut3d_interpolation_type interpolation,
> uint32_t flags);
> +int drm_plane_colorop_fixed_matrix_init(struct drm_device *dev, struct drm_colorop *colorop,
> + struct drm_plane *plane,
> + const struct drm_colorop_funcs *funcs,
> + u64 supported_fm, uint32_t flags);
>
> struct drm_colorop_state *
> drm_atomic_helper_colorop_duplicate_state(struct drm_colorop *colorop);
> @@ -480,6 +563,7 @@ drm_get_colorop_lut1d_interpolation_name(enum drm_colorop_lut1d_interpolation_ty
>
> const char *
> drm_get_colorop_lut3d_interpolation_name(enum drm_colorop_lut3d_interpolation_type type);
> +const char *drm_get_colorop_fixed_matrix_type_name(enum drm_colorop_fixed_matrix_type type);
>
> void drm_colorop_set_next_property(struct drm_colorop *colorop, struct drm_colorop *next);
>
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index a4bdc4bd11bc..dc4b8566fec8 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -971,6 +971,18 @@ enum drm_colorop_type {
> * color = lut3d[index]
> */
> DRM_COLOROP_3D_LUT,
> +
> + /**
> + * @DRM_COLOROP_FIXED_MATRIX:
> + *
> + * enum string "Fixed Matrix"
> + *
> + * A Colorop block that performs a pre-defined matrix operation selected
> + * via the FIXED_MATRIX_TYPE enum property. The driver advertises the supported
> + * operations through this property.
> + */
> + DRM_COLOROP_FIXED_MATRIX,
> +
> };
>
> /**