Re: [RFC PATCH v2 1/9] drm/colorop: Add DRM_COLOROP_CSC_FF

["Borah, Chaitanya Kumar" <chaitanya.kumar.borah@intel.com>]

Hello Harry,

On 3/30/2026 9:04 PM, Harry Wentland wrote:
> From: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
> 
> Introduce DRM_COLOROP_CSC_FF, a new colorop type representing a
> fixed-function Color Space Conversion (CSC) block.
> 
> Unlike CTM-based colorops, this block does not expose programmable
> coefficients. Instead, userspace selects one of the predefined
> hardware modes via a new CSC_FF_TYPE enum property. Supported modes
> include common YUV->RGB and RGB709->RGB2020 conversions.
> 

Thank you for incorporating this into your series. I believe this 
approach should work for both Intel and AMD hardware. I've posted a 
v2[1] of the patch addressing Pekka's comments. Please let me know if it 
looks good.

==
Chaitanya

[1] https://patchwork.freedesktop.org/patch/716856/?series=162787&rev=2

> 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     | 105 ++++++++++++++++++++++++++++++
>   include/drm/drm_colorop.h         |  72 ++++++++++++++++++++
>   include/uapi/drm/drm_mode.h       |  13 ++++
>   5 files changed, 198 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 41c57063f3b4..5bff85576e6b 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_CSC_FF:
> +		drm_printf(p, "\tcsc_ff_type=%s\n",
> +			   drm_get_colorop_csc_ff_type_name(state->csc_ff_type));
> +		break;
>   	default:
>   		break;
>   	}
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index 5bd5bf6661df..39b0dd1ec348 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->csc_ff_type_property) {
> +		state->csc_ff_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->csc_ff_type_property)
> +		*val = state->csc_ff_type;
>   	else
>   		return -EINVAL;
>   
> diff --git a/drivers/gpu/drm/drm_colorop.c b/drivers/gpu/drm/drm_colorop.c
> index 566816e3c6f0..6a345e2e8b15 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_CSC_FF, "CSC Fixed-Function"},
>   };
>   
>   static const char * const colorop_curve_1d_type_names[] = {
> @@ -90,6 +91,13 @@ static const struct drm_prop_enum_list drm_colorop_lut3d_interpolation_list[] =
>   	{ DRM_COLOROP_LUT3D_INTERPOLATION_TETRAHEDRAL, "Tetrahedral" },
>   };
>   
> +static const char * const colorop_csc_ff_type_names[] = {
> +	[DRM_COLOROP_CSC_FF_YUV601_RGB601]   = "YUV601 to RGB601",
> +	[DRM_COLOROP_CSC_FF_YUV709_RGB709]   = "YUV709 to RGB709",
> +	[DRM_COLOROP_CSC_FF_YUV2020_RGB2020] = "YUV2020 to RGB2020",
> +	[DRM_COLOROP_CSC_FF_RGB709_RGB2020]  = "RGB709 to RGB2020",
> +};
> +
>   /* Init Helpers */
>   
>   static int drm_plane_colorop_init(struct drm_device *dev, struct drm_colorop *colorop,
> @@ -455,6 +463,80 @@ int drm_plane_colorop_3dlut_init(struct drm_device *dev, struct drm_colorop *col
>   }
>   EXPORT_SYMBOL(drm_plane_colorop_3dlut_init);
>   
> +/**
> + * drm_plane_colorop_csc_ff_init - Initialize a DRM_COLOROP_CSC_FF
> + *
> + * @dev: DRM device
> + * @colorop: The drm_colorop object to initialize
> + * @plane: The associated drm_plane
> + * @funcs: control functions for the new colorop
> + * @supported_csc_ff: A bitfield of supported drm_plane_colorop_csc_ff_type enum values,
> + *                    created using BIT(csc_ff_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_csc_ff_init(struct drm_device *dev, struct drm_colorop *colorop,
> +				  struct drm_plane *plane, const struct drm_colorop_funcs *funcs,
> +				  u64 supported_csc_ff, uint32_t flags)
> +{
> +	struct drm_prop_enum_list enum_list[DRM_COLOROP_CSC_FF_COUNT];
> +	int i, len;
> +
> +	struct drm_property *prop;
> +	int ret;
> +
> +	if (!supported_csc_ff) {
> +		drm_err(dev,
> +			"No supported CSC op for new CSC FF colorop on [PLANE:%d:%s]\n",
> +			plane->base.id, plane->name);
> +		return -EINVAL;
> +	}
> +
> +	if ((supported_csc_ff & -BIT(DRM_COLOROP_CSC_FF_COUNT)) != 0) {
> +		drm_err(dev, "Unknown CSC provided on [PLANE:%d:%s]\n",
> +			plane->base.id, plane->name);
> +		return -EINVAL;
> +	}
> +
> +	ret = drm_plane_colorop_init(dev, colorop, plane, funcs, DRM_COLOROP_CSC_FF, flags);
> +	if (ret)
> +		return ret;
> +
> +	len = 0;
> +	for (i = 0; i < DRM_COLOROP_CSC_FF_COUNT; i++) {
> +		if ((supported_csc_ff & BIT(i)) == 0)
> +			continue;
> +
> +		enum_list[len].type = i;
> +		enum_list[len].name = colorop_csc_ff_type_names[i];
> +		len++;
> +	}
> +
> +	if (WARN_ON(len <= 0))
> +		return -EINVAL;
> +
> +	prop = drm_property_create_enum(dev, DRM_MODE_PROP_ATOMIC, "CSC_FF_TYPE",
> +					enum_list, len);
> +
> +	if (!prop)
> +		return -ENOMEM;
> +
> +	colorop->csc_ff_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->csc_ff_type_property,
> +				   enum_list[0].type);
> +	drm_colorop_reset(colorop);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_plane_colorop_csc_ff_init);
> +
>   static void __drm_atomic_helper_colorop_duplicate_state(struct drm_colorop *colorop,
>   							struct drm_colorop_state *state)
>   {
> @@ -521,6 +603,13 @@ static void __drm_colorop_state_reset(struct drm_colorop_state *colorop_state,
>   						      &val);
>   		colorop_state->curve_1d_type = val;
>   	}
> +
> +	if (colorop->csc_ff_type_property) {
> +		drm_object_property_get_default_value(&colorop->base,
> +						      colorop->csc_ff_type_property,
> +						      &val);
> +		colorop_state->csc_ff_type = val;
> +	}
>   }
>   
>   /**
> @@ -561,6 +650,7 @@ 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_CSC_FF] = "CSC Fixed-Function",
>   };
>   
>   static const char * const colorop_lu3d_interpolation_name[] = {
> @@ -617,6 +707,21 @@ const char *drm_get_colorop_lut3d_interpolation_name(enum drm_colorop_lut3d_inte
>   	return colorop_lu3d_interpolation_name[type];
>   }
>   
> +/**
> + * drm_get_colorop_csc_ff_type_name: return a string for interpolation type
> + * @type: csc ff 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_csc_ff_type_name(enum drm_colorop_csc_ff_type type)
> +{
> +	if (WARN_ON(type >= ARRAY_SIZE(colorop_csc_ff_type_names)))
> +		return "unknown";
> +
> +	return colorop_csc_ff_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..2cd8e0779c2a 100644
> --- a/include/drm/drm_colorop.h
> +++ b/include/drm/drm_colorop.h
> @@ -134,6 +134,60 @@ enum drm_colorop_curve_1d_type {
>   	DRM_COLOROP_1D_CURVE_COUNT
>   };
>   
> +/**
> + * enum drm_colorop_csc_ff_type - type of CSC Fixed-Function
> + *
> + * Describes a CSC operation to be applied by the DRM_COLOROP_CSC_FF colorop.
> + */
> +enum drm_colorop_csc_ff_type {
> +	/**
> +	 * @DRM_COLOROP_CSC_FF_YUV601_RGB601
> +	 *
> +	 * enum string "YUV601 to RGB601"
> +	 *
> +	 * Selects the fixed-function CSC preset that converts YUV
> +	 * (BT.601) colorimetry to RGB (BT.601).
> +	 */
> +	DRM_COLOROP_CSC_FF_YUV601_RGB601,
> +
> +	/**
> +	 * @DRM_COLOROP_CSC_FF_YUV709_RGB709:
> +	 *
> +	 * enum string "YUV709 to RGB709"
> +	 *
> +	 * Selects the fixed-function CSC preset that converts YUV
> +	 * (BT.709) colorimetry to RGB (BT.709).
> +	 */
> +	DRM_COLOROP_CSC_FF_YUV709_RGB709,
> +
> +	/**
> +	 * @DRM_COLOROP_CSC_FF_YUV2020_RGB2020:
> +	 *
> +	 * enum string "YUV2020 to RGB2020"
> +	 *
> +	 * Selects the fixed-function CSC preset that converts YUV
> +	 * (BT.2020) colorimetry to RGB (BT.2020).
> +	 */
> +	DRM_COLOROP_CSC_FF_YUV2020_RGB2020,
> +
> +	/**
> +	 * @DRM_COLOROP_CSC_FF_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_CSC_FF_RGB709_RGB2020,
> +
> +	/**
> +	 * @DRM_COLOROP_CSC_FF_COUNT:
> +	 *
> +	 * enum value denoting the size of the enum
> +	 */
> +	DRM_COLOROP_CSC_FF_COUNT
> +};
> +
>   /**
>    * struct drm_colorop_state - mutable colorop state
>    */
> @@ -183,6 +237,13 @@ struct drm_colorop_state {
>   	 */
>   	struct drm_property_blob *data;
>   
> +	/**
> +	 * @csc_ff_type:
> +	 *
> +	 * Type of Fixed function CSC.
> +	 */
> +	enum drm_colorop_csc_ff_type csc_ff_type;
> +
>   	/** @state: backpointer to global drm_atomic_state */
>   	struct drm_atomic_state *state;
>   };
> @@ -368,6 +429,13 @@ struct drm_colorop {
>   	 */
>   	struct drm_property *data_property;
>   
> +	/**
> +	 * @csc_ff_type_property:
> +	 *
> +	 * Sub-type for DRM_COLOROP_CSC_FF type.
> +	 */
> +	struct drm_property *csc_ff_type_property;
> +
>   	/**
>   	 * @next_property:
>   	 *
> @@ -424,6 +492,9 @@ 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_csc_ff_init(struct drm_device *dev, struct drm_colorop *colorop,
> +				  struct drm_plane *plane, const struct drm_colorop_funcs *funcs,
> +				  u64 supported_csc_ff, uint32_t flags);
>   
>   struct drm_colorop_state *
>   drm_atomic_helper_colorop_duplicate_state(struct drm_colorop *colorop);
> @@ -480,6 +551,7 @@ 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_csc_ff_type_name(enum drm_colorop_csc_ff_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..5d21f73c3d76 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -971,6 +971,19 @@ enum drm_colorop_type {
>   	 *         color = lut3d[index]
>   	 */
>   	DRM_COLOROP_3D_LUT,
> +
> +	/**
> +	 * @DRM_COLOROP_CSC_FF:
> +	 *
> +	 * enum string "CSC Fixed-Function"
> +	 *
> +	 * A fixed-function Color Space Conversion block where the coefficients
> +	 * are not programmable but selected from predefined hardware modes via
> +	 * the CSC_FF_TYPE enum property. The driver advertises the supported
> +	 * CSC modes through this property.
> +	 */
> +	DRM_COLOROP_CSC_FF,
> +
>   };
>   
>   /**