Re: [PATCH RFC v2 1/2] drm: Add optinal YCBCR_ENCODING property to drm_plane

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 04, 2017 at 10:14:25AM +0300, Jyri Sarha wrote:
> Add a standard optinal property to control YCbCr conversion in DRM
> planes. The property is stored to drm_plane object to allow different
> set of supported conversion modes for different planes on the device.
> 
> Signed-off-by: Jyri Sarha <jsarha@ti.com>
> ---
>  drivers/gpu/drm/drm_atomic.c     |  5 ++++
>  drivers/gpu/drm/drm_color_mgmt.c | 59 ++++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_plane.c      |  3 ++
>  include/drm/drm_color_mgmt.h     | 14 ++++++++++
>  include/drm/drm_plane.h          |  6 ++++
>  5 files changed, 87 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 4033384..bcef93d 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -732,6 +732,7 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
>  {
>  	struct drm_device *dev = plane->dev;
>  	struct drm_mode_config *config = &dev->mode_config;
> +	int ret;
>  
>  	if (property == config->prop_fb_id) {
>  		struct drm_framebuffer *fb = drm_framebuffer_lookup(dev, val);
> @@ -774,6 +775,8 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
>  		state->rotation = val;
>  	} else if (property == plane->zpos_property) {
>  		state->zpos = val;
> +	} else if (property == plane->ycbcr_encoding_property) {
> +		state->ycbcr_encoding = val;
>  	} else if (plane->funcs->atomic_set_property) {
>  		return plane->funcs->atomic_set_property(plane, state,
>  				property, val);
> @@ -834,6 +837,8 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
>  		*val = state->rotation;
>  	} else if (property == plane->zpos_property) {
>  		*val = state->zpos;
> +	} else if (property == plane->ycbcr_encoding_property) {
> +		*val = state->ycbcr_encoding;
>  	} else if (plane->funcs->atomic_get_property) {
>  		return plane->funcs->atomic_get_property(plane, state, property, val);
>  	} else {
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
> index 533f3a3..245b14a 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -33,6 +33,11 @@
>   * properties on the &drm_crtc object. They are set up by calling
>   * drm_crtc_enable_color_mgmt().
>   *
> + * Support for different YCbCr color encodings is controlled trough
> + * plane specific YCBCR_ENCODING property.
> + *
> + * The &drm_crtc object's properties are:
> + *
>   * "DEGAMMA_LUT”:
>   *	Blob property to set the degamma lookup table (LUT) mapping pixel data
>   *	from the framebuffer before it is given to the transformation matrix.
> @@ -85,6 +90,13 @@
>   * drm_mode_crtc_set_gamma_size(). Drivers which support both should use
>   * drm_atomic_helper_legacy_gamma_set() to alias the legacy gamma ramp with the
>   * "GAMMA_LUT" property above.
> + *
> + * The &drm_plane object's properties are:
> + *
> + * "YCBCR_ENCODING"
> + * 	Optional plane enum property to control YCbCr to RGB
> + * 	conversion. The driver provides a subset of standard
> + *	enum values supported by the DRM plane.
>   */
>  
>  /**
> @@ -333,3 +345,50 @@ int drm_mode_gamma_get_ioctl(struct drm_device *dev,
>  	drm_modeset_unlock(&crtc->mutex);
>  	return ret;
>  }
> +
> +static char *ycbcr_encoding_name[] = {
> +	[DRM_PLANE_YCBCR_BT601_FULL_RANGE] = "BT.601 full range",

Why full range for BT.601 but not the others?

I presume the full range here refers to the YCbCr data, and RGB will
always be full range? 

> +	[DRM_PLANE_YCBCR_BT601_LIMITED_RANGE] = "BT.601 limited range",
> +	[DRM_PLANE_YCBCR_BT709_LIMITED_RANGE] = "BT.709 limited range",
> +	[DRM_PLANE_YCBCR_BT2020_LIMITED_RANGE] = "BT.2020 limited range",
> +};
> +
> +/**
> + * drm_plane_create_ycbcr_properties - ycbcr related plane properties
> + * @enum_list: drm_prop_enum_list array of supported modes without names
> + * @enum_list_len: length of enum_list array
> + * @default_mode: default YCbCr encoding
> + *
> + * Create and attach plane specific YCBCR_ENCODING property to to the
> + * drm_plane object. The supported encodings should be provided in the
> + * enum_list parameter. The enum_list parameter should not contain the
> + * enum names, because the standard names are added by this function.
> + */
> +int drm_plane_create_ycbcr_properties(struct drm_plane *plane,
> +			struct drm_prop_enum_list *enum_list,
> +			unsigned int enum_list_len,

This API doesn't seem very nice because you have to pass in a
non-const enum list. Could we perhaps pass the supported values
as a bitmask instead? Or const int []?

> +			enum drm_plane_ycbcr_encoding default_mode)
> +{
> +	struct drm_device *dev = plane->dev;
> +	struct drm_property *prop;
> +	unsigned int i;
> +
> +	if (WARN_ON(plane->ycbcr_encoding_property != NULL))
> +		return -EEXIST;

We don't have those kinds of checks elsewhere, so why would we
want it here?

> +
> +	for (i = 0; i < enum_list_len; i++) {
> +		enum drm_plane_ycbcr_encoding encoding = enum_list[i].type;
> +
> +		enum_list[i].name = ycbcr_encoding_name[encoding];
> +	}
> +
> +	prop = drm_property_create_enum(dev, DRM_MODE_PROP_ATOMIC,
> +					"YCBCR_ENCODING",
> +					enum_list, enum_list_len);
> +	if (!prop)
> +		return -ENOMEM;
> +	plane->ycbcr_encoding_property = prop;
> +	drm_object_attach_property(&plane->base, prop, default_mode);

Missing the state->ycbcr_encoding setup.

> +
> +	return 0;
> +}
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index fedd4d6..007c4d7 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -244,6 +244,9 @@ void drm_plane_cleanup(struct drm_plane *plane)
>  
>  	kfree(plane->name);
>  
> +	if (plane->ycbcr_encoding_property)
> +		drm_property_destroy(dev, plane->ycbcr_encoding_property);
> +
>  	memset(plane, 0, sizeof(*plane));
>  }
>  EXPORT_SYMBOL(drm_plane_cleanup);
> diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
> index 03a59cb..1771394 100644
> --- a/include/drm/drm_color_mgmt.h
> +++ b/include/drm/drm_color_mgmt.h
> @@ -26,6 +26,8 @@
>  #include <linux/ctype.h>
>  
>  struct drm_crtc;
> +struct drm_plane;
> +struct drm_prop_enum_list;
>  
>  uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision);
>  
> @@ -37,4 +39,16 @@ void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
>  int drm_mode_crtc_set_gamma_size(struct drm_crtc *crtc,
>  				 int gamma_size);
>  
> +enum drm_plane_ycbcr_encoding {
> +	DRM_PLANE_YCBCR_BT601_FULL_RANGE = 0,
> +	DRM_PLANE_YCBCR_BT601_LIMITED_RANGE,
> +	DRM_PLANE_YCBCR_BT709_LIMITED_RANGE,
> +	DRM_PLANE_YCBCR_BT2020_LIMITED_RANGE,
> +};
> +
> +int drm_plane_create_ycbcr_properties(struct drm_plane *plane,
> +			struct drm_prop_enum_list *enum_list,
> +			unsigned int enum_list_len,
> +			enum drm_plane_ycbcr_encoding default_mode);
> +
>  #endif
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index 9ab3e70..4d0510f 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -26,6 +26,7 @@
>  #include <linux/list.h>
>  #include <linux/ctype.h>
>  #include <drm/drm_mode_object.h>
> +#include <drm/drm_color_mgmt.h>
>  
>  struct drm_crtc;
>  struct drm_printer;
> @@ -112,6 +113,9 @@ struct drm_plane_state {
>  	unsigned int zpos;
>  	unsigned int normalized_zpos;
>  
> +	/* YCbCr to RGB conversion */
> +	enum drm_plane_ycbcr_encoding ycbcr_encoding;
> +
>  	/* Clipped coordinates */
>  	struct drm_rect src, dst;
>  
> @@ -523,6 +527,8 @@ struct drm_plane {
>  
>  	struct drm_property *zpos_property;
>  	struct drm_property *rotation_property;
> +
> +	struct drm_property *ycbcr_encoding_property;
>  };
>  
>  #define obj_to_plane(x) container_of(x, struct drm_plane, base)
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC
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