Re: [PATCH RFC v2 04/20] drm/crtc: Add COLOR_PIPELINE property

[Louis Chauvet <louis.chauvet@bootlin.com>]

Le 18/09/2025 à 02:43, Nícolas F. R. A. Prado a écrit :
> Add a COLOR_PIPELINE property to the CRTC to allow userspace to set a
> post-blend color pipeline analogously to how pre-blend color pipelines
> are set on planes.
> 
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> ---
>   drivers/gpu/drm/drm_atomic_uapi.c | 49 +++++++++++++++++++++++++++++++++++----
>   drivers/gpu/drm/drm_crtc.c        | 33 ++++++++++++++++++++++++++
>   include/drm/drm_atomic_uapi.h     |  2 ++
>   include/drm/drm_crtc.h            | 11 +++++++++
>   4 files changed, 91 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index b7cc6945864274bedd21dd5b73494f9aae216888..063c142fd9b656e228cfc660d005a3fbb4640d32 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -287,6 +287,33 @@ drm_atomic_set_colorop_for_plane(struct drm_plane_state *plane_state,
>   }
>   EXPORT_SYMBOL(drm_atomic_set_colorop_for_plane);
>   
> +/**
> + * drm_atomic_set_colorop_for_crtc - set colorop for crtc
> + * @crtc_state: atomic state object for the crtc
> + * @colorop: colorop to use for the crtc
> + *
> + * Helper function to select the color pipeline on a crtc by setting
> + * it to the first drm_colorop element of the pipeline.
> + */
> +void
> +drm_atomic_set_colorop_for_crtc(struct drm_crtc_state *crtc_state,
> +				 struct drm_colorop *colorop)
> +{
> +	struct drm_crtc *crtc = crtc_state->crtc;
> +
> +	if (colorop)
> +		drm_dbg_atomic(crtc->dev,
> +			       "Set [COLOROP:%d] for [CRTC:%d:%s] state %p\n",
> +			       colorop->base.id, crtc->base.id, crtc->name,
> +			       crtc_state);
> +	else
> +		drm_dbg_atomic(crtc->dev,
> +			       "Set [NOCOLOROP] for [CRTC:%d:%s] state %p\n",
> +			       crtc->base.id, crtc->name, crtc_state);
> +
> +	crtc_state->color_pipeline = colorop;
> +}
> +EXPORT_SYMBOL(drm_atomic_set_colorop_for_crtc);
>   
>   /**
>    * drm_atomic_set_crtc_for_connector - set CRTC for connector
> @@ -396,8 +423,8 @@ static s32 __user *get_out_fence_for_connector(struct drm_atomic_state *state,
>   }
>   
>   static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
> -		struct drm_crtc_state *state, struct drm_property *property,
> -		uint64_t val)
> +		struct drm_crtc_state *state, struct drm_file *file_priv,
> +		struct drm_property *property, uint64_t val)
>   {
>   	struct drm_device *dev = crtc->dev;
>   	struct drm_mode_config *config = &dev->mode_config;
> @@ -406,7 +433,17 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   
>   	if (property == config->prop_active)
>   		state->active = val;
> -	else if (property == config->prop_mode_id) {
> +	else if (property == crtc->color_pipeline_property) {
> +		/* find DRM colorop object */
> +		struct drm_colorop *colorop = NULL;
> +
> +		colorop = drm_colorop_find(dev, file_priv, val);
> +
> +		if (val && !colorop)
> +			return -EACCES;
> +
> +		drm_atomic_set_colorop_for_crtc(state, colorop);

I don't know if this is needed, but you added a warning/early return for 
ctm/degamma_lut if file_priv->post_blend_color_pipeline is true.

Does it make sense to add this?

	if (!file_priv->post_blend_color_pipeline) {
			drm_dbg_atomic(dev,
				"Setting COLOR_PIPELINE property not permitted without 
DRM_CLIENT_CAP_POST_BLEND_COLOR_PIPELINE client cap\n");
			return -EINVAL;
		}

> +	} else if (property == config->prop_mode_id) {
>   		struct drm_property_blob *mode =
>   			drm_property_lookup_blob(dev, val);
>   		ret = drm_atomic_set_mode_prop_for_crtc(state, mode);
> @@ -487,6 +524,8 @@ drm_atomic_crtc_get_property(struct drm_crtc *crtc,
>   		*val = 0;
>   	else if (property == crtc->scaling_filter_property)
>   		*val = state->scaling_filter;
> +	else if (property == crtc->color_pipeline_property)
> +		*val = (state->color_pipeline) ? state->color_pipeline->base.id : 0;
>   	else if (crtc->funcs->atomic_get_property)
>   		return crtc->funcs->atomic_get_property(crtc, state, property, val);
>   	else {
> @@ -1047,6 +1086,8 @@ int drm_atomic_get_property(struct drm_mode_object *obj,
>   
>   		if (colorop->plane)
>   			WARN_ON(!drm_modeset_is_locked(&colorop->plane->mutex));
> +		else if (colorop->crtc)
> +			WARN_ON(!drm_modeset_is_locked(&colorop->crtc->mutex));
>   
>   		ret = drm_atomic_colorop_get_property(colorop,
>   				colorop->state, property, val);
> @@ -1204,7 +1245,7 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
>   		}
>   
>   		ret = drm_atomic_crtc_set_property(crtc,
> -				crtc_state, prop, prop_value);
> +				crtc_state, file_priv, prop, prop_value);
>   		break;
>   	}
>   	case DRM_MODE_OBJECT_PLANE: {
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 94e60cffd29972aa979ac2f1932be7a6a97f3ada..94238163ff1254c721df39c030bc99a31d3bb92a 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1003,3 +1003,36 @@ drm_common_create_color_pipeline_property(struct drm_device *dev, struct drm_mod
>   	kfree(all_pipelines);
>   	return prop;
>   }
> +
> +/**
> + * drm_crtc_create_color_pipeline_property - create a new color pipeline
> + * property
> + *
> + * @crtc: drm CRTC
> + * @pipelines: list of pipelines
> + * @num_pipelines: number of pipelines
> + *
> + * Create the COLOR_PIPELINE CRTC property to specify color pipelines on
> + * the CRTC.
> + *
> + * RETURNS:
> + * Zero for success or -errno
> + */
> +int drm_crtc_create_color_pipeline_property(struct drm_crtc *crtc,
> +					    const struct drm_prop_enum_list *pipelines,
> +					    int num_pipelines)
> +{
> +	struct drm_property *prop;
> +
> +	prop = drm_common_create_color_pipeline_property(crtc->dev,
> +							 &crtc->base,
> +							 pipelines,
> +							 num_pipelines);
> +	if (IS_ERR(prop))
> +		return PTR_ERR(prop);
> +
> +	crtc->color_pipeline_property = prop;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_crtc_create_color_pipeline_property);
> diff --git a/include/drm/drm_atomic_uapi.h b/include/drm/drm_atomic_uapi.h
> index 4363155233267b93767c895fa6085544e2277442..4dc191f6f929d73deee9812025c48275a33cf770 100644
> --- a/include/drm/drm_atomic_uapi.h
> +++ b/include/drm/drm_atomic_uapi.h
> @@ -52,6 +52,8 @@ void drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
>   				 struct drm_framebuffer *fb);
>   void drm_atomic_set_colorop_for_plane(struct drm_plane_state *plane_state,
>   				      struct drm_colorop *colorop);
> +void drm_atomic_set_colorop_for_crtc(struct drm_crtc_state *crtc_state,
> +				     struct drm_colorop *colorop);
>   int __must_check
>   drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
>   				  struct drm_crtc *crtc);
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 77c0c04a5910a2263923e06cf37535697e20e1c9..df03637ca25abd45e96b5944229297f776fd046d 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -1096,6 +1096,14 @@ struct drm_crtc {
>   	 */
>   	struct drm_property *scaling_filter_property;
>   
> +	/**
> +	 * @color_pipeline_property:
> +	 *
> +	 * Optional "COLOR_PIPELINE" enum property for specifying
> +	 * a color pipeline to use on the CRTC.
> +	 */
> +	struct drm_property *color_pipeline_property;
> +
>   	/**
>   	 * @state:
>   	 *
> @@ -1331,5 +1339,8 @@ static inline struct drm_crtc *drm_crtc_find(struct drm_device *dev,
>   
>   int drm_crtc_create_scaling_filter_property(struct drm_crtc *crtc,
>   					    unsigned int supported_filters);
> +int drm_crtc_create_color_pipeline_property(struct drm_crtc *crtc,
> +					     const struct drm_prop_enum_list *pipelines,
> +					     int num_pipelines);
>   bool drm_crtc_in_clone_mode(struct drm_crtc_state *crtc_state);
>   #endif /* __DRM_CRTC_H__ */
> 

-- 
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com