drm: introduce pipe color correction properties

Patch based on a previous series by Shashank Sharma.

This introduces optional properties to enable color correction at the
pipe level. It relies on 3 transformations applied to every pixels
displayed. First a lookup into a degamma table, then a multiplication
of the rgb components by a 3x3 matrix and finally another lookup into
a gamma table.

The following properties can be added to a pipe :
  - DEGAMMA_LUT : blob containing degamma LUT
  - DEGAMMA_LUT_SIZE : number of elements in DEGAMMA_LUT
  - CTM : transformation matrix applied after the degamma LUT
  - GAMMA_LUT : blob containing gamma LUT
  - GAMMA_LUT_SIZE : number of elements in GAMMA_LUT

DEGAMMA_LUT_SIZE and GAMMA_LUT_SIZE are read only properties, set by
the driver to tell userspace applications what sizes should be the
lookup tables in DEGAMMA_LUT and GAMMA_LUT.

A helper is also provided so legacy gamma correction is redirected
through these new properties.

v2: Register LUT size properties as range

v3: Fix round in drm_color_lut_get_value() helper
    More docs on how degamma/gamma properties are used

v4: Update contributors

v5: Rename CTM_MATRIX property to CTM (Doh!)
    Add legacy gamma_set atomic helper
    Describe CTM/LUT acronyms in the kernel doc

v6: Fix missing blob unref in drm_atomic_helper_crtc_reset

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Kumar, Kiran S <kiran.s.kumar@intel.com>
Signed-off-by: Kausal Malladi <kausalmalladi@gmail.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Rob Bradford <robert.bradford@intel.com>
[danvet: CrOS maintainers are also happy with the userspacde side:
https://codereview.chromium.org/1182063002/ ]
Reviewed-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1456506302-640-4-git-send-email-lionel.g.landwerlin@intel.com

3 files changed, 51 insertions, 1 deletions

diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index fe5efad..9054598c 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -146,6 +146,9 @@ __drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
 					    struct drm_connector_state *state);
 void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
 					  struct drm_connector_state *state);
+void drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
+					u16 *red, u16 *green, u16 *blue,
+					uint32_t start, uint32_t size);
 
 /**
  * drm_atomic_crtc_for_each_plane - iterate over planes currently attached to CRTC
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 75b28de..b10eba23a 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -305,6 +305,8 @@ struct drm_plane_helper_funcs;
  * @mode_changed: crtc_state->mode or crtc_state->enable has been changed
  * @active_changed: crtc_state->active has been toggled.
  * @connectors_changed: connectors to this crtc have been updated
+ * @color_mgmt_changed: color management properties have changed (degamma or
+ *	gamma LUT or CSC matrix)
  * @plane_mask: bitmask of (1 << drm_plane_index(plane)) of attached planes
  * @connector_mask: bitmask of (1 << drm_connector_index(connector)) of attached connectors
  * @encoder_mask: bitmask of (1 << drm_encoder_index(encoder)) of attached encoders
@@ -312,6 +314,11 @@ struct drm_plane_helper_funcs;
  * 	update to ensure framebuffer cleanup isn't done too early
  * @adjusted_mode: for use by helpers and drivers to compute adjusted mode timings
  * @mode: current mode timings
+ * @degamma_lut: Lookup table for converting framebuffer pixel data
+ *	before apply the conversion matrix
+ * @ctm: Transformation matrix
+ * @gamma_lut: Lookup table for converting pixel data after the
+ *	conversion matrix
  * @event: optional pointer to a DRM event to signal upon completion of the
  * 	state update
  * @state: backpointer to global drm_atomic_state
@@ -333,6 +340,7 @@ struct drm_crtc_state {
 	bool mode_changed : 1;
 	bool active_changed : 1;
 	bool connectors_changed : 1;
+	bool color_mgmt_changed : 1;
 
 	/* attached planes bitmask:
 	 * WARNING: transitional helpers do not maintain plane_mask so
@@ -355,6 +363,11 @@ struct drm_crtc_state {
 	/* blob property to expose current mode to atomic userspace */
 	struct drm_property_blob *mode_blob;
 
+	/* blob property to expose color management to userspace */
+	struct drm_property_blob *degamma_lut;
+	struct drm_property_blob *ctm;
+	struct drm_property_blob *gamma_lut;
+
 	struct drm_pending_vblank_event *event;
 
 	struct drm_atomic_state *state;
@@ -757,7 +770,7 @@ struct drm_crtc {
 	int x, y;
 	const struct drm_crtc_funcs *funcs;
 
-	/* CRTC gamma size for reporting to userspace */
+	/* Legacy FB CRTC gamma size for reporting to userspace */
 	uint32_t gamma_size;
 	uint16_t *gamma_store;
 
@@ -2027,6 +2040,15 @@ struct drm_mode_config_funcs {
  * @property_blob_list: list of all the blob property objects
  * @blob_lock: mutex for blob property allocation and management
  * @*_property: core property tracking
+ * @degamma_lut_property: LUT used to convert the framebuffer's colors to linear
+ *	gamma
+ * @degamma_lut_size_property: size of the degamma LUT as supported by the
+ *	driver (read-only)
+ * @ctm_property: Matrix used to convert colors after the lookup in the
+ *	degamma LUT
+ * @gamma_lut_property: LUT used to convert the colors, after the CSC matrix, to
+ *	the gamma space of the connected screen (read-only)
+ * @gamma_lut_size_property: size of the gamma LUT as supported by the driver
  * @preferred_depth: preferred RBG pixel depth, used by fb helpers
  * @prefer_shadow: hint to userspace to prefer shadow-fb rendering
  * @async_page_flip: does this device support async flips on the primary plane?
@@ -2128,6 +2150,13 @@ struct drm_mode_config {
 	struct drm_property *aspect_ratio_property;
 	struct drm_property *dirty_info_property;
 
+	/* Optional color correction properties */
+	struct drm_property *degamma_lut_property;
+	struct drm_property *degamma_lut_size_property;
+	struct drm_property *ctm_property;
+	struct drm_property *gamma_lut_property;
+	struct drm_property *gamma_lut_size_property;
+
 	/* properties for virtual machine layout */
 	struct drm_property *suggested_x_property;
 	struct drm_property *suggested_y_property;
@@ -2550,6 +2579,21 @@ static inline struct drm_property *drm_property_find(struct drm_device *dev,
 	return mo ? obj_to_property(mo) : NULL;
 }
 
+/*
+ * Extract a degamma/gamma LUT value provided by user and round it to the
+ * precision supported by the hardware.
+ */
+static inline uint32_t drm_color_lut_extract(uint32_t user_input,
+					     uint32_t bit_precision)
+{
+	uint32_t val = user_input + (1 << (16 - bit_precision - 1));
+	uint32_t max = 0xffff >> (16 - bit_precision);
+
+	val >>= 16 - bit_precision;
+
+	return clamp_val(val, 0, max);
+}
+
 /* Plane list iterator for legacy (overlay only) planes. */
 #define drm_for_each_legacy_plane(plane, dev) \
 	list_for_each_entry(plane, &(dev)->mode_config.plane_list, head) \
diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index 4b37afa..97fa894 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -48,6 +48,9 @@ extern bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
 				     struct drm_display_mode *mode,
 				     int x, int y,
 				     struct drm_framebuffer *old_fb);
+extern void drm_helper_crtc_enable_color_mgmt(struct drm_crtc *crtc,
+					      int degamma_lut_size,
+					      int gamma_lut_size);
 extern bool drm_helper_crtc_in_use(struct drm_crtc *crtc);
 extern bool drm_helper_encoder_in_use(struct drm_encoder *encoder);