Re: [PATCH V11 06/47] drm/colorop: Add 1D Curve subtype

["Sebastian Wick" <sebastian.wick@redhat.com>]

On Fri Aug 15, 2025 at 5:49 AM CEST, Alex Hung wrote:
> From: Harry Wentland <harry.wentland@amd.com>
>
> Add a new drm_colorop with DRM_COLOROP_1D_CURVE with two subtypes:
> DRM_COLOROP_1D_CURVE_SRGB_EOTF and DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF.
>
> Reviewed-by: Simon Ser <contact@emersion.fr>
> Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Signed-off-by: Harry Wentland <harry.wentland@amd.com>
> Co-developed-by: Alex Hung <alex.hung@amd.com>
> Signed-off-by: Alex Hung <alex.hung@amd.com>
> Reviewed-by: Daniel Stone <daniels@collabora.com>
> Reviewed-by: Melissa Wen <mwen@igalia.com>
> ---
> V9: Specify function names by _plane_ (Chaitanya Kumar Borah)
>
> v5:
>  - Add drm_get_colorop_curve_1d_type_name in header
>  - Add drm_colorop_init
>  - Set default curve
>  - Add kernel docs
>
> v4:
>  - Use drm_colorop_curve_1d_type_enum_list to get name (Pekka)
>  - Create separate init function for 1D curve
>  - Pass supported TFs into 1D curve init function
>
>  drivers/gpu/drm/drm_atomic_uapi.c |  18 ++--
>  drivers/gpu/drm/drm_colorop.c     | 134 ++++++++++++++++++++++++++++++
>  include/drm/drm_colorop.h         |  63 ++++++++++++++
>  3 files changed, 210 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index ad2043f16268..52b5a9b5523e 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -650,11 +650,17 @@ static int drm_atomic_colorop_set_property(struct drm_colorop *colorop,
>  		struct drm_colorop_state *state, struct drm_file *file_priv,
>  		struct drm_property *property, uint64_t val)
>  {
> -	drm_dbg_atomic(colorop->dev,
> -			"[COLOROP:%d] unknown property [PROP:%d:%s]]\n",
> -			colorop->base.id,
> -			property->base.id, property->name);
> -	return -EINVAL;
> +	if (property == colorop->curve_1d_type_property) {
> +		state->curve_1d_type = val;
> +	} else {
> +		drm_dbg_atomic(colorop->dev,
> +			       "[COLOROP:%d:%d] unknown property [PROP:%d:%s]]\n",
> +			       colorop->base.id, colorop->type,
> +			       property->base.id, property->name);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
>  }
>  
>  static int
> @@ -664,6 +670,8 @@ drm_atomic_colorop_get_property(struct drm_colorop *colorop,
>  {
>  	if (property == colorop->type_property) {
>  		*val = colorop->type;
> +	} else if (property == colorop->curve_1d_type_property) {
> +		*val = state->curve_1d_type;
>  	} else {
>  		return -EINVAL;
>  	}
> diff --git a/drivers/gpu/drm/drm_colorop.c b/drivers/gpu/drm/drm_colorop.c
> index 1459a28c7e7b..6fbc3c284d33 100644
> --- a/drivers/gpu/drm/drm_colorop.c
> +++ b/drivers/gpu/drm/drm_colorop.c
> @@ -31,6 +31,123 @@
>  
>  #include "drm_crtc_internal.h"
>  
> +static const struct drm_prop_enum_list drm_colorop_type_enum_list[] = {
> +	{ DRM_COLOROP_1D_CURVE, "1D Curve" },
> +};
> +
> +static const char * const colorop_curve_1d_type_names[] = {
> +	[DRM_COLOROP_1D_CURVE_SRGB_EOTF] = "sRGB EOTF",
> +	[DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF] = "sRGB Inverse EOTF",
> +};
> +
> +
> +/* Init Helpers */
> +
> +static int drm_plane_colorop_init(struct drm_device *dev, struct drm_colorop *colorop,
> +			    struct drm_plane *plane, enum drm_colorop_type type)
> +{
> +	struct drm_mode_config *config = &dev->mode_config;
> +	struct drm_property *prop;
> +	int ret = 0;
> +
> +	ret = drm_mode_object_add(dev, &colorop->base, DRM_MODE_OBJECT_COLOROP);
> +	if (ret)
> +		return ret;
> +
> +	colorop->base.properties = &colorop->properties;
> +	colorop->dev = dev;
> +	colorop->type = type;
> +	colorop->plane = plane;
> +
> +	list_add_tail(&colorop->head, &config->colorop_list);
> +	colorop->index = config->num_colorop++;
> +
> +	/* add properties */
> +
> +	/* type */
> +	prop = drm_property_create_enum(dev,
> +					DRM_MODE_PROP_IMMUTABLE,
> +					"TYPE", drm_colorop_type_enum_list,
> +					ARRAY_SIZE(drm_colorop_type_enum_list));
> +
> +	if (!prop)
> +		return -ENOMEM;
> +
> +	colorop->type_property = prop;
> +
> +	drm_object_attach_property(&colorop->base,
> +				   colorop->type_property,
> +				   colorop->type);
> +
> +	return ret;
> +}
> +
> +/**
> + * drm_plane_colorop_curve_1d_init - Initialize a DRM_COLOROP_1D_CURVE
> + *
> + * @dev: DRM device
> + * @colorop: The drm_colorop object to initialize
> + * @plane: The associated drm_plane
> + * @supported_tfs: A bitfield of supported drm_plane_colorop_curve_1d_init enum values,
> + *                 created using BIT(curve_type) and combined with the OR '|'
> + *                 operator.
> + * @return zero on success, -E value on failure
> + */
> +int drm_plane_colorop_curve_1d_init(struct drm_device *dev, struct drm_colorop *colorop,
> +				    struct drm_plane *plane, u64 supported_tfs)
> +{
> +	struct drm_prop_enum_list enum_list[DRM_COLOROP_1D_CURVE_COUNT];
> +	int i, len;
> +
> +	struct drm_property *prop;
> +	int ret;
> +
> +	if (!supported_tfs) {
> +		drm_err(dev,
> +			"No supported TFs for new 1D curve colorop on [PLANE:%d:%s]\n",
> +			plane->base.id, plane->name);
> +		return -EINVAL;
> +	}
> +
> +	if ((supported_tfs & -BIT(DRM_COLOROP_1D_CURVE_COUNT)) != 0) {
> +		drm_err(dev, "Unknown TF provided on [PLANE:%d:%s]\n",
> +			plane->base.id, plane->name);
> +		return -EINVAL;
> +	}
> +
> +	ret = drm_plane_colorop_init(dev, colorop, plane, DRM_COLOROP_1D_CURVE);
> +	if (ret)
> +		return ret;
> +
> +	len = 0;
> +	for (i = 0; i < DRM_COLOROP_1D_CURVE_COUNT; i++) {
> +		if ((supported_tfs & BIT(i)) == 0)
> +			continue;
> +
> +		enum_list[len].type = i;
> +		enum_list[len].name = colorop_curve_1d_type_names[i];
> +		len++;
> +	}
> +
> +	if (WARN_ON(len <= 0))
> +		return -EINVAL;
> +
> +
> +	/* initialize 1D curve only attribute */
> +	prop = drm_property_create_enum(dev, DRM_MODE_PROP_ATOMIC, "CURVE_1D_TYPE",
> +					enum_list, len);
> +	if (!prop)
> +		return -ENOMEM;
> +
> +	colorop->curve_1d_type_property = prop;
> +	drm_object_attach_property(&colorop->base, colorop->curve_1d_type_property,
> +				   enum_list[0].type);
> +	drm_colorop_reset(colorop);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_plane_colorop_curve_1d_init);
> +
>  static void __drm_atomic_helper_colorop_duplicate_state(struct drm_colorop *colorop,
>  							struct drm_colorop_state *state)
>  {
> @@ -70,7 +187,16 @@ void drm_colorop_atomic_destroy_state(struct drm_colorop *colorop,
>  static void __drm_colorop_state_reset(struct drm_colorop_state *colorop_state,
>  				      struct drm_colorop *colorop)
>  {
> +	u64 val;
> +
>  	colorop_state->colorop = colorop;
> +
> +	if (colorop->curve_1d_type_property) {
> +		drm_object_property_get_default_value(&colorop->base,
> +						colorop->curve_1d_type_property,
> +						&val);
> +		colorop_state->curve_1d_type = val;
> +	}
>  }
>  
>  /**
> @@ -114,3 +240,11 @@ const char *drm_get_colorop_type_name(enum drm_colorop_type type)
>  
>  	return colorop_type_name[type];
>  }
> +
> +const char *drm_get_colorop_curve_1d_type_name(enum drm_colorop_curve_1d_type type)
> +{
> +	if (WARN_ON(type >= ARRAY_SIZE(colorop_curve_1d_type_names)))
> +		return "unknown";
> +
> +	return colorop_curve_1d_type_names[type];
> +}
> diff --git a/include/drm/drm_colorop.h b/include/drm/drm_colorop.h
> index 9c9698545f63..fa167e642e0d 100644
> --- a/include/drm/drm_colorop.h
> +++ b/include/drm/drm_colorop.h
> @@ -31,6 +31,42 @@
>  #include <drm/drm_mode.h>
>  #include <drm/drm_property.h>
>  
> +
> +/**
> + * enum drm_colorop_curve_1d_type - type of 1D curve
> + *
> + * Describes a 1D curve to be applied by the DRM_COLOROP_1D_CURVE colorop.
> + */
> +enum drm_colorop_curve_1d_type {
> +	/**
> +	 * @DRM_COLOROP_1D_CURVE_SRGB_EOTF:
> +	 *
> +	 * enum string "sRGB EOTF"
> +	 *
> +	 * sRGB piece-wise electro-optical transfer function. Transfer
> +	 * characteristics as defined by IEC 61966-2-1 sRGB. Equivalent
> +	 * to H.273 TransferCharacteristics code point 13 with
> +	 * MatrixCoefficients set to 0.
> +	 */

We user space folks have been convinced at this point that the sRGB EOTF
is actually gamma 2.2, and not the piece-wise function. Now, if the
hardware is actually the piece-wise, then that's what should be exposed,
but I'm a bit unsure if we should do that under the name sRGB EOTF.

Maybe any other alternative is even worse. At least this is clearly
documented to be the piece-wise function, so it's only about the naming.

> +	DRM_COLOROP_1D_CURVE_SRGB_EOTF,
> +
> +	/**
> +	 * @DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF:
> +	 *
> +	 * enum string "sRGB Inverse EOTF"
> +	 *
> +	 * The inverse of &DRM_COLOROP_1D_CURVE_SRGB_EOTF
> +	 */
> +	DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF,
> +
> +	/**
> +	 * @DRM_COLOROP_1D_CURVE_COUNT:
> +	 *
> +	 * enum value denoting the size of the enum
> +	 */
> +	DRM_COLOROP_1D_CURVE_COUNT
> +};
> +
>  /**
>   * struct drm_colorop_state - mutable colorop state
>   */
> @@ -46,6 +82,13 @@ struct drm_colorop_state {
>  	 * information.
>  	 */
>  
> +	/**
> +	 * @curve_1d_type:
> +	 *
> +	 * Type of 1D curve.
> +	 */
> +	enum drm_colorop_curve_1d_type curve_1d_type;
> +
>  	/** @state: backpointer to global drm_atomic_state */
>  	struct drm_atomic_state *state;
>  };
> @@ -127,6 +170,14 @@ struct drm_colorop {
>  	 * this color operation. The type is enum drm_colorop_type.
>  	 */
>  	struct drm_property *type_property;
> +
> +	/**
> +	 * @curve_1d_type_property:
> +	 *
> +	 * Sub-type for DRM_COLOROP_1D_CURVE type.
> +	 */
> +	struct drm_property *curve_1d_type_property;
> +
>  };
>  
>  #define obj_to_colorop(x) container_of(x, struct drm_colorop, base)
> @@ -151,6 +202,9 @@ static inline struct drm_colorop *drm_colorop_find(struct drm_device *dev,
>  	return mo ? obj_to_colorop(mo) : NULL;
>  }
>  
> +int drm_plane_colorop_curve_1d_init(struct drm_device *dev, struct drm_colorop *colorop,
> +				    struct drm_plane *plane, u64 supported_tfs);
> +
>  struct drm_colorop_state *
>  drm_atomic_helper_colorop_duplicate_state(struct drm_colorop *colorop);
>  
> @@ -191,4 +245,13 @@ static inline unsigned int drm_colorop_index(const struct drm_colorop *colorop)
>   */
>  const char *drm_get_colorop_type_name(enum drm_colorop_type type);
>  
> +/**
> + * drm_get_colorop_curve_1d_type_name - return a string for 1D curve type
> + * @type: 1d curve 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_curve_1d_type_name(enum drm_colorop_curve_1d_type type);
> +
>  #endif /* __DRM_COLOROP_H__ */