[PATCHv2 1/5] drm: Introduce the blend-func property

[Vandita Kulkarni]

From: Damien Lespiau <damien.lespiau at intel.com>

We'd like to be able to program the blending modes of display planes.
Ville suggested to use something similar to the GL blend states, which
does seem like a good idea.

For now, we only consider blend factors, but room is left for
extensions: blend equation, separate rgb/alpha blend factors, blend
color.

V2: Added the belnd func property support in get property.

Suggested-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
Signed-off-by: Vandita Kulkarni <vandita.kulkarni at intel.com>
---
 Documentation/DocBook/gpu.tmpl | 11 +++++++++--
 drivers/gpu/drm/drm_atomic.c   | 14 ++++++++++++++
 drivers/gpu/drm/drm_crtc.c     |  5 +++++
 include/drm/drm_crtc.h         | 20 ++++++++++++++++++++
 4 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
index 1464fb2..f673989 100644
--- a/Documentation/DocBook/gpu.tmpl
+++ b/Documentation/DocBook/gpu.tmpl
@@ -1816,7 +1816,7 @@ void intel_crt_init(struct drm_device *dev)
 	<td valign="top" >Description/Restrictions</td>
 	</tr>
 	<tr>
-	<td rowspan="42" valign="top" >DRM</td>
+	<td rowspan="43" valign="top" >DRM</td>
 	<td valign="top" >Generic</td>
 	<td valign="top" >“rotation”</td>
 	<td valign="top" >BITMASK</td>
@@ -1868,7 +1868,7 @@ void intel_crt_init(struct drm_device *dev)
 	<td valign="top" >CRTC that connector is attached to (atomic)</td>
 	</tr>
 	<tr>
-	<td rowspan="11" valign="top" >Plane</td>
+	<td rowspan="12" valign="top" >Plane</td>
 	<td valign="top" >“type”</td>
 	<td valign="top" >ENUM | IMMUTABLE</td>
 	<td valign="top" >{ "Overlay", "Primary", "Cursor" }</td>
@@ -1946,6 +1946,13 @@ void intel_crt_init(struct drm_device *dev)
 	<td valign="top" >CRTC that plane is attached to (atomic)</td>
 	</tr>
 	<tr>
+	<td valign="top" >“blend_func”</td>
+	<td valign="top" >None</td>
+	<td valign="top" >DRM_BLEND_FUNC()</td>
+	<td valign="top" >Plane</td>
+	<td valign="top" >Source and destination blending factors</td>
+	</tr>
+	<tr>
 	<td rowspan="2" valign="top" >DVI-I</td>
 	<td valign="top" >“subconnector”</td>
 	<td valign="top" >ENUM</td>
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 8ee1db8..c2ead2d 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -701,6 +701,18 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
 		state->src_h = val;
 	} else if (property == config->rotation_property) {
 		state->rotation = val;
+	} else if (property == config->prop_blend_func) {
+		enum drm_blend_factor src_factor, dst_factor;
+
+		src_factor = DRM_BLEND_FUNC_SRC_FACTOR(val);
+		dst_factor = DRM_BLEND_FUNC_DST_FACTOR(val);
+
+		if (src_factor != dst_factor &&
+			(src_factor == DRM_BLEND_FACTOR_AUTO ||
+			dst_factor == DRM_BLEND_FACTOR_AUTO))
+			return -EINVAL;
+
+		state->blend_mode.func = val & GENMASK(31, 0);
 	} else if (plane->funcs->atomic_set_property) {
 		return plane->funcs->atomic_set_property(plane, state,
 				property, val);
@@ -757,6 +769,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
 		*val = state->src_h;
 	} else if (property == config->rotation_property) {
 		*val = state->rotation;
+	} else if (property == config->prop_blend_func) {
+		*val = state->blend_mode.func;
 	} 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_crtc.c b/drivers/gpu/drm/drm_crtc.c
index f7fe9e1..2cac5e1 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1587,6 +1587,11 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
 		return -ENOMEM;
 	dev->mode_config.gamma_lut_size_property = prop;
 
+	prop = drm_property_create_range(dev, 0, "blend_func", 0, U32_MAX);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.prop_blend_func = prop;
+
 	return 0;
 }
 
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 6d46842..269f660 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -89,6 +89,23 @@ static inline uint64_t I642U64(int64_t val)
 #define DRM_REFLECT_X	4
 #define DRM_REFLECT_Y	5
 
+enum drm_blend_factor {
+	DRM_BLEND_FACTOR_AUTO,
+	DRM_BLEND_FACTOR_ZERO,
+	DRM_BLEND_FACTOR_ONE,
+	DRM_BLEND_FACTOR_SRC_ALPHA,
+	DRM_BLEND_FACTOR_ONE_MINUS_SRC_ALPHA,
+};
+
+#define DRM_BLEND_FUNC(src_factor, dst_factor)		\
+	(DRM_BLEND_FACTOR_##src_factor << 16 | DRM_BLEND_FACTOR_##dst_factor)
+#define DRM_BLEND_FUNC_SRC_FACTOR(val)	(((val) >> 16) & 0xffff)
+#define DRM_BLEND_FUNC_DST_FACTOR(val)	((val) & 0xffff)
+
+struct drm_blend_mode {
+	uint64_t func;
+};
+
 enum drm_connector_force {
 	DRM_FORCE_UNSPECIFIED,
 	DRM_FORCE_OFF,
@@ -1273,6 +1290,8 @@ struct drm_plane_state {
 	/* Plane rotation */
 	unsigned int rotation;
 
+	struct drm_blend_mode blend_mode;
+
 	struct drm_atomic_state *state;
 };
 
@@ -2125,6 +2144,7 @@ struct drm_mode_config {
 	struct drm_property *prop_crtc_id;
 	struct drm_property *prop_active;
 	struct drm_property *prop_mode_id;
+	struct drm_property *prop_blend_func;
 
 	/* DVI-I properties */
 	struct drm_property *dvi_i_subconnector_property;
-- 
1.9.1