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 <[e-mail]>
Signed-off-by: Kumar, Kiran S <[e-mail]>
Signed-off-by: Kausal Malladi <[e-mail]>
Signed-off-by: Lionel Landwerlin <[e-mail]>
Reviewed-by: Matt Roper <[e-mail]>
Acked-by: Rob Bradford <[e-mail]>
[danvet: CrOS maintainers are also happy with the userspacde side:
https://codereview.chromium.org/1182063002/ ]
Reviewed-by: Daniel Stone <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/DocBook/gpu.tmpl

···
 	<td valign="top" >Description/Restrictions</td>
 	</tr>
 	<tr>
-	<td rowspan="37" valign="top" >DRM</td>
+	<td rowspan="42" valign="top" >DRM</td>
 	<td valign="top" >Generic</td>
 	<td valign="top" >“rotation”</td>
 	<td valign="top" >BITMASK</td>
···
 	<td valign="top" >property to suggest an Y offset for a connector</td>
 	</tr>
 	<tr>
-	<td rowspan="3" valign="top" >Optional</td>
+	<td rowspan="8" valign="top" >Optional</td>
 	<td valign="top" >“scaling mode”</td>
 	<td valign="top" >ENUM</td>
 	<td valign="top" >{ "None", "Full", "Center", "Full aspect" }</td>
···
 	<td valign="top" >{ "Off", "On", "Annotate" }</td>
 	<td valign="top" >Connector</td>
 	<td valign="top" >TBD</td>
+	</tr>
+	<tr>
+	<td valign="top" >“DEGAMMA_LUT”</td>
+	<td valign="top" >BLOB</td>
+	<td valign="top" >0</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to set the degamma lookup table
+		(LUT) mapping pixel data from the framebuffer before it is
+		given to the transformation matrix. The data is an interpreted
+		as an array of struct drm_color_lut elements. Hardware might
+		choose not to use the full precision of the LUT elements nor
+		use all the elements of the LUT (for example the hardware
+		might choose to interpolate between LUT[0] and LUT[4]). </td>
+	</tr>
+	<tr>
+	<td valign="top" >“DEGAMMA_LUT_SIZE”</td>
+	<td valign="top" >RANGE | IMMUTABLE</td>
+	<td valign="top" >Min=0, Max=UINT_MAX</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to gives the size of the lookup
+		table to be set on the DEGAMMA_LUT property (the size depends
+		on the underlying hardware).</td>
+	</tr>
+	<tr>
+	<td valign="top" >“CTM”</td>
+	<td valign="top" >BLOB</td>
+	<td valign="top" >0</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to set the current
+		transformation matrix (CTM) apply to pixel data after the
+		lookup through the degamma LUT and before the lookup through
+		the gamma LUT. The data is an interpreted as a struct
+		drm_color_ctm.</td>
+	</tr>
+	<tr>
+	<td valign="top" >“GAMMA_LUT”</td>
+	<td valign="top" >BLOB</td>
+	<td valign="top" >0</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to set the gamma lookup table
+		(LUT) mapping pixel data after to the transformation matrix to
+		data sent to the connector. The data is an interpreted as an
+		array of struct drm_color_lut elements. Hardware might choose
+		not to use the full precision of the LUT elements nor use all
+		the elements of the LUT (for example the hardware might choose
+		to interpolate between LUT[0] and LUT[4]).</td>
+	</tr>
+	<tr>
+	<td valign="top" >“GAMMA_LUT_SIZE”</td>
+	<td valign="top" >RANGE | IMMUTABLE</td>
+	<td valign="top" >Min=0, Max=UINT_MAX</td>
+	<td valign="top" >CRTC</td>
+	<td valign="top" >DRM property to gives the size of the lookup
+		table to be set on the GAMMA_LUT property (the size depends on
+		the underlying hardware).</td>
 	</tr>
 	<tr>
 	<td rowspan="20" valign="top" >i915</td>

drivers/gpu/drm/drm_atomic.c

···
 
 #include <drm/drmP.h>
 #include <drm/drm_atomic.h>
+#include <drm/drm_mode.h>
 #include <drm/drm_plane_helper.h>
 
 /**
···
 EXPORT_SYMBOL(drm_atomic_set_mode_prop_for_crtc);
 
 /**
+ * drm_atomic_replace_property_blob - replace a blob property
+ * @blob: a pointer to the member blob to be replaced
+ * @new_blob: the new blob to replace with
+ * @expected_size: the expected size of the new blob
+ * @replaced: whether the blob has been replaced
+ *
+ * RETURNS:
+ * Zero on success, error code on failure
+ */
+static void
+drm_atomic_replace_property_blob(struct drm_property_blob **blob,
+				 struct drm_property_blob *new_blob,
+				 bool *replaced)
+{
+	struct drm_property_blob *old_blob = *blob;
+
+	if (old_blob == new_blob)
+		return;
+
+	if (old_blob)
+		drm_property_unreference_blob(old_blob);
+	if (new_blob)
+		drm_property_reference_blob(new_blob);
+	*blob = new_blob;
+	*replaced = true;
+
+	return;
+}
+
+static int
+drm_atomic_replace_property_blob_from_id(struct drm_crtc *crtc,
+					 struct drm_property_blob **blob,
+					 uint64_t blob_id,
+					 ssize_t expected_size,
+					 bool *replaced)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_property_blob *new_blob = NULL;
+
+	if (blob_id != 0) {
+		new_blob = drm_property_lookup_blob(dev, blob_id);
+		if (new_blob == NULL)
+			return -EINVAL;
+		if (expected_size > 0 && expected_size != new_blob->length)
+			return -EINVAL;
+	}
+
+	drm_atomic_replace_property_blob(blob, new_blob, replaced);
+
+	return 0;
+}
+
+/**
  * drm_atomic_crtc_set_property - set property on CRTC
  * @crtc: the drm CRTC to set a property on
  * @state: the state object to update with the new property value
···
 {
 	struct drm_device *dev = crtc->dev;
 	struct drm_mode_config *config = &dev->mode_config;
+	bool replaced = false;
 	int ret;
 
 	if (property == config->prop_active)
···
 		ret = drm_atomic_set_mode_prop_for_crtc(state, mode);
 		drm_property_unreference_blob(mode);
 		return ret;
-	}
-	else if (crtc->funcs->atomic_set_property)
+	} else if (property == config->degamma_lut_property) {
+		ret = drm_atomic_replace_property_blob_from_id(crtc,
+					&state->degamma_lut,
+					val,
+					-1,
+					&replaced);
+		state->color_mgmt_changed = replaced;
+		return ret;
+	} else if (property == config->ctm_property) {
+		ret = drm_atomic_replace_property_blob_from_id(crtc,
+					&state->ctm,
+					val,
+					sizeof(struct drm_color_ctm),
+					&replaced);
+		state->color_mgmt_changed = replaced;
+		return ret;
+	} else if (property == config->gamma_lut_property) {
+		ret = drm_atomic_replace_property_blob_from_id(crtc,
+					&state->gamma_lut,
+					val,
+					-1,
+					&replaced);
+		state->color_mgmt_changed = replaced;
+		return ret;
+	} else if (crtc->funcs->atomic_set_property)
 		return crtc->funcs->atomic_set_property(crtc, state, property, val);
 	else
 		return -EINVAL;
···
 		*val = state->active;
 	else if (property == config->prop_mode_id)
 		*val = (state->mode_blob) ? state->mode_blob->base.id : 0;
+	else if (property == config->degamma_lut_property)
+		*val = (state->degamma_lut) ? state->degamma_lut->base.id : 0;
+	else if (property == config->ctm_property)
+		*val = (state->ctm) ? state->ctm->base.id : 0;
+	else if (property == config->gamma_lut_property)
+		*val = (state->gamma_lut) ? state->gamma_lut->base.id : 0;
 	else if (crtc->funcs->atomic_get_property)
 		return crtc->funcs->atomic_get_property(crtc, state, property, val);
 	else

drivers/gpu/drm/drm_atomic_helper.c

···
  */
 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
 {
-	if (crtc->state)
+	if (crtc->state) {
 		drm_property_unreference_blob(crtc->state->mode_blob);
+		drm_property_unreference_blob(crtc->state->degamma_lut);
+		drm_property_unreference_blob(crtc->state->ctm);
+		drm_property_unreference_blob(crtc->state->gamma_lut);
+	}
 	kfree(crtc->state);
 	crtc->state = kzalloc(sizeof(*crtc->state), GFP_KERNEL);
 
···
 
 	if (state->mode_blob)
 		drm_property_reference_blob(state->mode_blob);
+	if (state->degamma_lut)
+		drm_property_reference_blob(state->degamma_lut);
+	if (state->ctm)
+		drm_property_reference_blob(state->ctm);
+	if (state->gamma_lut)
+		drm_property_reference_blob(state->gamma_lut);
 	state->mode_changed = false;
 	state->active_changed = false;
 	state->planes_changed = false;
 	state->connectors_changed = false;
+	state->color_mgmt_changed = false;
 	state->event = NULL;
 }
 EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);
···
 					    struct drm_crtc_state *state)
 {
 	drm_property_unreference_blob(state->mode_blob);
+	drm_property_unreference_blob(state->degamma_lut);
+	drm_property_unreference_blob(state->ctm);
+	drm_property_unreference_blob(state->gamma_lut);
 }
 EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);
 
···
 	kfree(state);
 }
 EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
+
+/**
+ * drm_atomic_helper_legacy_gamma_set - set the legacy gamma correction table
+ * @crtc: CRTC object
+ * @red: red correction table
+ * @green: green correction table
+ * @blue: green correction table
+ * @start:
+ * @size: size of the tables
+ *
+ * Implements support for legacy gamma correction table for drivers
+ * that support color management through the DEGAMMA_LUT/GAMMA_LUT
+ * properties.
+ */
+void drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
+					u16 *red, u16 *green, u16 *blue,
+					uint32_t start, uint32_t size)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_mode_config *config = &dev->mode_config;
+	struct drm_atomic_state *state;
+	struct drm_crtc_state *crtc_state;
+	struct drm_property_blob *blob = NULL;
+	struct drm_color_lut *blob_data;
+	int i, ret = 0;
+
+	state = drm_atomic_state_alloc(crtc->dev);
+	if (!state)
+		return;
+
+	blob = drm_property_create_blob(dev,
+					sizeof(struct drm_color_lut) * size,
+					NULL);
+	if (!blob) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	/* Prepare GAMMA_LUT with the legacy values. */
+	blob_data = (struct drm_color_lut *) blob->data;
+	for (i = 0; i < size; i++) {
+		blob_data[i].red = red[i];
+		blob_data[i].green = green[i];
+		blob_data[i].blue = blue[i];
+	}
+
+	state->acquire_ctx = crtc->dev->mode_config.acquire_ctx;
+retry:
+	crtc_state = drm_atomic_get_crtc_state(state, crtc);
+	if (IS_ERR(crtc_state)) {
+		ret = PTR_ERR(crtc_state);
+		goto fail;
+	}
+
+	/* Reset DEGAMMA_LUT and CTM properties. */
+	ret = drm_atomic_crtc_set_property(crtc, crtc_state,
+			config->degamma_lut_property, 0);
+	if (ret)
+		goto fail;
+
+	ret = drm_atomic_crtc_set_property(crtc, crtc_state,
+			config->ctm_property, 0);
+	if (ret)
+		goto fail;
+
+	ret = drm_atomic_crtc_set_property(crtc, crtc_state,
+			config->gamma_lut_property, blob->base.id);
+	if (ret)
+		goto fail;
+
+	ret = drm_atomic_commit(state);
+	if (ret)
+		goto fail;
+
+	/* Driver takes ownership of state on successful commit. */
+
+	drm_property_unreference_blob(blob);
+
+	return;
+fail:
+	if (ret == -EDEADLK)
+		goto backoff;
+
+	drm_atomic_state_free(state);
+	drm_property_unreference_blob(blob);
+
+	return;
+backoff:
+	drm_atomic_state_clear(state);
+	drm_atomic_legacy_backoff(state);
+
+	goto retry;
+}
+EXPORT_SYMBOL(drm_atomic_helper_legacy_gamma_set);

drivers/gpu/drm/drm_crtc.c

···
 		return -ENOMEM;
 	dev->mode_config.prop_mode_id = prop;
 
+	prop = drm_property_create(dev,
+			DRM_MODE_PROP_BLOB,
+			"DEGAMMA_LUT", 0);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.degamma_lut_property = prop;
+
+	prop = drm_property_create_range(dev,
+			DRM_MODE_PROP_IMMUTABLE,
+			"DEGAMMA_LUT_SIZE", 0, UINT_MAX);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.degamma_lut_size_property = prop;
+
+	prop = drm_property_create(dev,
+			DRM_MODE_PROP_BLOB,
+			"CTM", 0);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.ctm_property = prop;
+
+	prop = drm_property_create(dev,
+			DRM_MODE_PROP_BLOB,
+			"GAMMA_LUT", 0);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.gamma_lut_property = prop;
+
+	prop = drm_property_create_range(dev,
+			DRM_MODE_PROP_IMMUTABLE,
+			"GAMMA_LUT_SIZE", 0, UINT_MAX);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.gamma_lut_size_property = prop;
+
 	return 0;
 }
 

drivers/gpu/drm/drm_crtc_helper.c

···
 	return drm_plane_helper_commit(plane, plane_state, old_fb);
 }
 EXPORT_SYMBOL(drm_helper_crtc_mode_set_base);
+
+/**
+ * drm_helper_crtc_enable_color_mgmt - enable color management properties
+ * @crtc: DRM CRTC
+ * @degamma_lut_size: the size of the degamma lut (before CSC)
+ * @gamma_lut_size: the size of the gamma lut (after CSC)
+ *
+ * This function lets the driver enable the color correction properties on a
+ * CRTC. This includes 3 degamma, csc and gamma properties that userspace can
+ * set and 2 size properties to inform the userspace of the lut sizes.
+ */
+void drm_helper_crtc_enable_color_mgmt(struct drm_crtc *crtc,
+				       int degamma_lut_size,
+				       int gamma_lut_size)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_mode_config *config = &dev->mode_config;
+
+	drm_object_attach_property(&crtc->base,
+				   config->degamma_lut_property, 0);
+	drm_object_attach_property(&crtc->base,
+				   config->ctm_property, 0);
+	drm_object_attach_property(&crtc->base,
+				   config->gamma_lut_property, 0);
+
+	drm_object_attach_property(&crtc->base,
+				   config->degamma_lut_size_property,
+				   degamma_lut_size);
+	drm_object_attach_property(&crtc->base,
+				   config->gamma_lut_size_property,
+				   gamma_lut_size);
+}
+EXPORT_SYMBOL(drm_helper_crtc_enable_color_mgmt);

include/drm/drm_atomic_helper.h

···
 					    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

include/drm/drm_crtc.h

···
  * @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
···
  * 	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
···
 	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
···
 
 	/* 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;
 
···
 	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;
 
···
  * @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?
···
 	struct drm_property *scaling_mode_property;
 	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_mode_object *mo;
 	mo = drm_mode_object_find(dev, id, DRM_MODE_OBJECT_PROPERTY);
 	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. */

include/drm/drm_crtc_helper.h

···
 				     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);
 

include/uapi/drm/drm_mode.h

···
 	__u64 blue;
 };
 
+struct drm_color_ctm {
+	/* Conversion matrix in S31.32 format. */
+	__s64 matrix[9];
+};
+
+struct drm_color_lut {
+	/*
+	 * Data is U0.16 fixed point format.
+	 */
+	__u16 red;
+	__u16 green;
+	__u16 blue;
+	__u16 reserved;
+};
+
 #define DRM_MODE_PAGE_FLIP_EVENT 0x01
 #define DRM_MODE_PAGE_FLIP_ASYNC 0x02
 #define DRM_MODE_PAGE_FLIP_FLAGS (DRM_MODE_PAGE_FLIP_EVENT|DRM_MODE_PAGE_FLIP_ASYNC)