Date:   Fri, 6 Jul 2018 14:11:44 +0200
From:   Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        dri-devel@...ts.freedesktop.org,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cc:     Thomas Hellstrom <thellstrom@...are.com>,
        Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        Ben Skeggs <bskeggs@...hat.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        linux-tegra@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [RFC PATCH v3 1/2] drm: Add generic colorkey properties for DRM
 planes

Hey,

Op 04-06-18 om 00:00 schreef Dmitry Osipenko:
> From: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
>
> Color keying is the action of replacing pixels matching a given color
> (or range of colors) with transparent pixels in an overlay when
> performing blitting. Depending on the hardware capabilities, the
> matching pixel can either become fully transparent or gain adjustment
> of the pixels component values.
>
> Color keying is found in a large number of devices whose capabilities
> often differ, but they still have enough common features in range to
> standardize color key properties. This commit adds three generic DRM plane
> properties related to the color keying, providing initial color keying
> support.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/gpu/drm/drm_atomic.c | 12 +++++
>  drivers/gpu/drm/drm_blend.c  | 99 ++++++++++++++++++++++++++++++++++++
>  include/drm/drm_blend.h      |  3 ++
>  include/drm/drm_plane.h      | 53 +++++++++++++++++++
>  4 files changed, 167 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 895741e9cd7d..b322cbed319b 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -799,6 +799,12 @@ static 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->colorkey.mode_property) {
> +		state->colorkey.mode = val;
> +	} else if (property == plane->colorkey.min_property) {
> +		state->colorkey.min = val;
> +	} else if (property == plane->colorkey.max_property) {
> +		state->colorkey.max = val;
>  	} else if (property == plane->color_encoding_property) {
>  		state->color_encoding = val;
>  	} else if (property == plane->color_range_property) {
> @@ -864,6 +870,12 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
>  		*val = state->rotation;
>  	} else if (property == plane->zpos_property) {
>  		*val = state->zpos;
> +	} else if (property == plane->colorkey.mode_property) {
> +		*val = state->colorkey.mode;
> +	} else if (property == plane->colorkey.min_property) {
> +		*val = state->colorkey.min;
> +	} else if (property == plane->colorkey.max_property) {
> +		*val = state->colorkey.max;
>  	} else if (property == plane->color_encoding_property) {
>  		*val = state->color_encoding;
>  	} else if (property == plane->color_range_property) {
> diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
> index a16a74d7e15e..12fed2ff65c8 100644
> --- a/drivers/gpu/drm/drm_blend.c
> +++ b/drivers/gpu/drm/drm_blend.c
> @@ -107,6 +107,11 @@
>   *	planes. Without this property the primary plane is always below the cursor
>   *	plane, and ordering between all other planes is undefined.
>   *
> + * colorkey:
> + *	Color keying is set up with drm_plane_create_colorkey_properties().
> + *	It adds support for replacing a range of colors with a transparent
> + *	color in the plane.
> + *
>   * Note that all the property extensions described here apply either to the
>   * plane or the CRTC (e.g. for the background color, which currently is not
>   * exposed and assumed to be black).
> @@ -448,3 +453,97 @@ int drm_atomic_normalize_zpos(struct drm_device *dev,
>  	return 0;
>  }
>  EXPORT_SYMBOL(drm_atomic_normalize_zpos);
> +
> +static const char * const plane_colorkey_mode_name[] = {
> +	[DRM_PLANE_COLORKEY_MODE_DISABLED] = "disabled",
> +	[DRM_PLANE_COLORKEY_MODE_FOREGROUND_CLIP] = "foreground-clip",
> +};
> +
> +/**
> + * drm_plane_create_colorkey_properties - create colorkey properties
> + * @plane: drm plane
> + * @supported_modes: bitmask of supported color keying modes
> + *
> + * This function creates the generic color keying properties and attach them to
> + * the plane to enable color keying control for blending operations.
> + *
> + * Color keying is controlled by these properties:
> + *
> + * colorkey.mode:
> + *	The mode is an enumerated property that controls how color keying
> + *	operates.
> + *
> + * colorkey.min, colorkey.max:
> + *	These two properties specify the colors that are treated as the color
> + *	key. Pixel whose value is in the [min, max] range is the color key
> + *	matching pixel. The minimum and maximum values are expressed as a
> + *	64-bit integer in ARGB16161616 format, where A is the alpha value and
> + *	R, G and B correspond to the color components. Drivers shall convert
> + *	ARGB16161616 value into appropriate format within planes atomic check.
> + *
> + *	When a single color key is desired instead of a range, userspace shall
> + *	set the min and max properties to the same value.
> + *
> + *	Drivers return an error from their plane atomic check if range can't be
> + *	handled.
> + *
> + * Returns:
> + * Zero on success, negative errno on failure.
> + */
> +int drm_plane_create_colorkey_properties(struct drm_plane *plane,
> +					 u32 supported_modes)
> +{
> +	struct drm_prop_enum_list modes_list[DRM_PLANE_COLORKEY_MODES_NUM];
> +	struct drm_property *mode_prop;
> +	struct drm_property *min_prop;
> +	struct drm_property *max_prop;
> +	unsigned int modes_num = 0;
> +	unsigned int i;
> +
> +	/* modes are driver-specific, build the list of supported modes */
> +	for (i = 0; i < DRM_PLANE_COLORKEY_MODES_NUM; i++) {
> +		if (!(supported_modes & BIT(i)))
> +			continue;
> +
> +		modes_list[modes_num].name = plane_colorkey_mode_name[i];
> +		modes_list[modes_num].type = i;
> +		modes_num++;
> +	}
> +
> +	/* at least one mode should be supported */
> +	if (!modes_num)
> +		return -EINVAL;
> +
> +	mode_prop = drm_property_create_enum(plane->dev, 0, "colorkey.mode",
> +					     modes_list, modes_num);
> +	if (!mode_prop)
> +		return -ENOMEM;
> +
> +	min_prop = drm_property_create_range(plane->dev, 0, "colorkey.min",
> +					     0, U64_MAX);
> +	if (!min_prop)
> +		goto err_destroy_mode_prop;
> +
> +	max_prop = drm_property_create_range(plane->dev, 0, "colorkey.max",
> +					     0, U64_MAX);
> +	if (!max_prop)
> +		goto err_destroy_min_prop;
> +
> +	drm_object_attach_property(&plane->base, mode_prop, 0);
> +	drm_object_attach_property(&plane->base, min_prop, 0);
> +	drm_object_attach_property(&plane->base, max_prop, 0);
> +
> +	plane->colorkey.mode_property = mode_prop;
> +	plane->colorkey.min_property = min_prop;
> +	plane->colorkey.max_property = max_prop;
> +
> +	return 0;
> +
> +err_destroy_min_prop:
> +	drm_property_destroy(plane->dev, min_prop);
> +err_destroy_mode_prop:
> +	drm_property_destroy(plane->dev, mode_prop);
> +
> +	return -ENOMEM;
> +}
> +EXPORT_SYMBOL(drm_plane_create_colorkey_properties);
> diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
> index 330c561c4c11..8e80d33b643e 100644
> --- a/include/drm/drm_blend.h
> +++ b/include/drm/drm_blend.h
> @@ -52,4 +52,7 @@ int drm_plane_create_zpos_immutable_property(struct drm_plane *plane,
>  					     unsigned int zpos);
>  int drm_atomic_normalize_zpos(struct drm_device *dev,
>  			      struct drm_atomic_state *state);
> +
> +int drm_plane_create_colorkey_properties(struct drm_plane *plane,
> +					 u32 supported_modes);
>  #endif
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index 26fa50c2a50e..9a621e1ccc47 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -32,6 +32,48 @@ struct drm_crtc;
>  struct drm_printer;
>  struct drm_modeset_acquire_ctx;
>  
> +/**
> + * enum drm_plane_colorkey_mode - uapi plane colorkey mode enumeration
> + */
> +enum drm_plane_colorkey_mode {
> +	/**
> +	 * @DRM_PLANE_COLORKEY_MODE_DISABLED:
> +	 *
> +	 * No color matching performed in this mode.
> +	 */
> +	DRM_PLANE_COLORKEY_MODE_DISABLED,
> +
> +	/**
> +	 * @DRM_PLANE_COLORKEY_MODE_FOREGROUND_CLIP:
> +	 *
> +	 * This mode is also known as a "green screen". Plane pixels are
> +	 * transparent in areas where pixels match a given color key range
> +	 * and there is a bottom (background) plane, in other cases plane
> +	 * pixels are unaffected.
> +	 *
> +	 */
> +	DRM_PLANE_COLORKEY_MODE_FOREGROUND_CLIP,
Could we add background clip as well?

Would be nice if we could map i915's legacy ioctl handler to the new color key mode.
> +	/**
> +	 * @DRM_PLANE_COLORKEY_MODES_NUM:
> +	 *
> +	 * Total number of color keying modes.
> +	 */
> +	DRM_PLANE_COLORKEY_MODES_NUM,
> +};
> +
> +/**
> + * struct drm_plane_colorkey_state - plane color keying state
> + * @colorkey.mode: color keying mode
> + * @colorkey.min: color key range minimum (in ARGB16161616 format)
> + * @colorkey.max: color key range maximum (in ARGB16161616 format)
> + */
> +struct drm_plane_colorkey_state {
> +	enum drm_plane_colorkey_mode mode;
> +	u64 min;
> +	u64 max;
> +};
Could we have some macros to extract the components for min/max?
A, R, G, B.

~Maarten

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