Re: [PATCH v3 06/21] drm: Introduce DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE

[Robert Mader <robert.mader@collabora.com>]

Hi, thanks for the series!

On 23.12.25 19:01, Ariel D'Alessandro wrote:
> From: "Nícolas F. R. A. Prado" <nfraprado@collabora.com>
>
> Introduce DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE which a DRM client can set
> to enable the usage of CRTC (post-blend) color pipelines instead of the
> now deprecated CRTC color management properties: "GAMMA_LUT",
> "DEGAMMA_LUT" and "CTM".
>
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> Co-developed-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
> Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
> Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
> ---
>   drivers/gpu/drm/drm_atomic_uapi.c   | 20 ++++++++++++++++++++
>   drivers/gpu/drm/drm_connector.c     |  1 +
>   drivers/gpu/drm/drm_crtc_internal.h |  1 +
>   drivers/gpu/drm/drm_ioctl.c         |  9 +++++++++
>   drivers/gpu/drm/drm_mode_object.c   |  9 +++++++++
>   include/drm/drm_file.h              |  7 +++++++
>   include/uapi/drm/drm.h              | 19 +++++++++++++++++++
>   7 files changed, 66 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index 07d0d224fe58c..d1bc78b2567a9 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -433,6 +433,11 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   	if (property == config->prop_active)
>   		state->active = val;
>   	else if (property == crtc->color_pipeline_property) {
> +		if (!file_priv->crtc_color_pipeline) {
> +			drm_dbg_atomic(dev,
> +				"Setting COLOR_PIPELINE CRTC property not permitted without DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE client cap\n");
> +			return -EINVAL;
> +		}
>   		/* find DRM colorop object */
>   		struct drm_colorop *colorop = NULL;
>   
> @@ -451,6 +456,11 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   	} else if (property == config->prop_vrr_enabled) {
>   		state->vrr_enabled = val;
>   	} else if (property == config->degamma_lut_property) {
> +		if (file_priv->crtc_color_pipeline) {
> +			drm_dbg_atomic(dev,
> +				"Setting DEGAMMA_LUT CRTC property not permitted with DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE client cap\n");
> +			return -EINVAL;
> +		}
>   		ret = drm_property_replace_blob_from_id(dev,
>   					&state->degamma_lut,
>   					val,
> @@ -459,6 +469,11 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   		state->color_mgmt_changed |= replaced;
>   		return ret;
>   	} else if (property == config->ctm_property) {
> +		if (file_priv->crtc_color_pipeline) {
> +			drm_dbg_atomic(dev,
> +				"Setting CTM CRTC property not permitted with DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE client cap\n");
> +			return -EINVAL;
> +		}
>   		ret = drm_property_replace_blob_from_id(dev,
>   					&state->ctm,
>   					val,
> @@ -467,6 +482,11 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   		state->color_mgmt_changed |= replaced;
>   		return ret;
>   	} else if (property == config->gamma_lut_property) {
> +		if (file_priv->crtc_color_pipeline) {
> +			drm_dbg_atomic(dev,
> +				"Setting GAMMA_LUT CRTC property not permitted with DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE client cap\n");
> +			return -EINVAL;
> +		}
>   		ret = drm_property_replace_blob_from_id(dev,
>   					&state->gamma_lut,
>   					val,
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 4d6dc9ebfdb5b..aec8a5c0d593a 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -3440,6 +3440,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>   	 */
>   	ret = drm_mode_object_get_properties(&connector->base, file_priv->atomic,
>   			file_priv->plane_color_pipeline,
> +			file_priv->crtc_color_pipeline,
>   			(uint32_t __user *)(unsigned long)(out_resp->props_ptr),
>   			(uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr),
>   			&out_resp->count_props);
> diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
> index c094092296448..ab02e6295271d 100644
> --- a/drivers/gpu/drm/drm_crtc_internal.h
> +++ b/drivers/gpu/drm/drm_crtc_internal.h
> @@ -164,6 +164,7 @@ void drm_mode_object_unregister(struct drm_device *dev,
>   				struct drm_mode_object *object);
>   int drm_mode_object_get_properties(struct drm_mode_object *obj, bool atomic,
>   				   bool plane_color_pipeline,
> +				   bool crtc_color_pipeline,
>   				   uint32_t __user *prop_ptr,
>   				   uint64_t __user *prop_values,
>   				   uint32_t *arg_count_props);
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index 2884075660ddd..14746afd82783 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -383,6 +383,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
>   			return -EINVAL;
>   		file_priv->plane_color_pipeline = req->value;
>   		break;
> +	case DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE:
> +		if (!file_priv->atomic)
> +			return -EINVAL;
> +		if (req->value > 1)
> +			return -EINVAL;
> +		if (!drm_core_check_feature(dev, DRIVER_CRTC_COLOR_PIPELINE))
> +			return -EINVAL;

For DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE we just solved the equivalent 
problem by checking if drivers actually expose pipelines (see 
https://lore.kernel.org/dri-devel/20260703073230.19982-1-robert.mader@collabora.com/ 
which just landed drm-misc-fixes and is marked for backporting). I 
initially went with the same approach of using a driver feature (see 
https://lore.kernel.org/dri-devel/20260630084229.529682-2-robert.mader@collabora.com/), 
however the explicit check turned out to be both sufficient and simpler. 
Using that approach would allow you to drop the patches 5, 17 and 21.

Regards

> +		file_priv->crtc_color_pipeline = req->value;
> +		break;
>   	default:
>   		return -EINVAL;
>   	}
> diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
> index b45d501b10c86..ea4508f6a09a6 100644
> --- a/drivers/gpu/drm/drm_mode_object.c
> +++ b/drivers/gpu/drm/drm_mode_object.c
> @@ -388,6 +388,7 @@ EXPORT_SYMBOL(drm_object_property_get_default_value);
>   /* helper for getconnector and getproperties ioctls */
>   int drm_mode_object_get_properties(struct drm_mode_object *obj, bool atomic,
>   				   bool plane_color_pipeline,
> +				   bool crtc_color_pipeline,
>   				   uint32_t __user *prop_ptr,
>   				   uint64_t __user *prop_values,
>   				   uint32_t *arg_count_props)
> @@ -416,6 +417,13 @@ int drm_mode_object_get_properties(struct drm_mode_object *obj, bool atomic,
>   				continue;
>   		}
>   
> +		if (!crtc_color_pipeline && obj->type == DRM_MODE_OBJECT_CRTC) {
> +			struct drm_crtc *crtc = obj_to_crtc(obj);
> +
> +			if (prop == crtc->color_pipeline_property)
> +				continue;
> +		}
> +
>   		if (*arg_count_props > count) {
>   			ret = __drm_object_property_get_value(obj, prop, &val);
>   			if (ret)
> @@ -475,6 +483,7 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data,
>   
>   	ret = drm_mode_object_get_properties(obj, file_priv->atomic,
>   			file_priv->plane_color_pipeline,
> +			file_priv->crtc_color_pipeline,
>   			(uint32_t __user *)(unsigned long)(arg->props_ptr),
>   			(uint64_t __user *)(unsigned long)(arg->prop_values_ptr),
>   			&arg->count_props);
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 6ee70ad65e1fd..d0c323378ae46 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -214,6 +214,13 @@ struct drm_file {
>   	 */
>   	bool plane_color_pipeline;
>   
> +	/**
> +	 * @crtc_color_pipeline:
> +	 *
> +	 * True if client understands CRTC (post-blend) color pipelines
> +	 */
> +	bool crtc_color_pipeline;
> +
>   	/**
>   	 * @was_master:
>   	 *
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index d726828bdf408..991ef14c5377c 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -927,6 +927,25 @@ struct drm_get_cap {
>    */
>   #define DRM_CLIENT_CAP_PLANE_COLOR_PIPELINE	7
>   
> +/**
> + * DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE
> + *
> + * If set to 1 the DRM core will allow setting the COLOR_PIPELINE
> + * property on a &drm_crtc, as well as drm_colorop properties.
> + *
> + * Setting of these crtc properties will be rejected when this client
> + * cap is set:
> + * - GAMMA_LUT
> + * - DEGAMMA_LUT
> + * - CTM
> + *
> + * The client must enable &DRM_CLIENT_CAP_ATOMIC first.
> + *
> + * This client cap can only be set if the driver sets the corresponding driver
> + * cap &DRM_CAP_CRTC_COLOR_PIPELINE.
> + */
> +#define DRM_CLIENT_CAP_CRTC_COLOR_PIPELINE	8
> +
>   /* DRM_IOCTL_SET_CLIENT_CAP ioctl argument type */
>   struct drm_set_client_cap {
>   	__u64 capability;
>
-- 
Robert Mader
Consultant Software Developer

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