[v2 03/25] drm: Add Enhanced LUT precision structure

[Uma Shankar]

Existing LUT precision structure is having only 16 bit
precision. This is not enough for upcoming enhanced hardwares
and advance usecases like HDR processing. Hence added a new
structure with 32 bit precision values.

Signed-off-by: Uma Shankar <uma.shankar at intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>
---
 drivers/gpu/drm/drm_color_mgmt.c | 43 ++++++++++++++++++++++++++++++++
 include/drm/drm_color_mgmt.h     | 13 ++++++++++
 include/uapi/drm/drm_mode.h      | 18 +++++++++++++
 3 files changed, 74 insertions(+)

diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index 3969dc548cff..83dc850d3b54 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -630,3 +630,46 @@ int drm_color_lut_check(const struct drm_property_blob *lut, u32 tests)
 	return 0;
 }
 EXPORT_SYMBOL(drm_color_lut_check);
+
+/**
+ * drm_color_lut_32_check - check validity of extended lookup table
+ * @lut: property blob containing extended LUT to check
+ * @tests: bitmask of tests to run
+ *
+ * Helper to check whether a userspace-provided extended lookup table is valid and
+ * satisfies hardware requirements.  Drivers pass a bitmask indicating which of
+ * the tests in &drm_color_lut_tests should be performed.
+ *
+ * Returns 0 on success, -EINVAL on failure.
+ */
+int drm_color_lut_32_check(const struct drm_property_blob *lut, u32 tests)
+{
+	const struct drm_color_lut_32 *entry;
+	int i;
+
+	if (!lut || !tests)
+		return 0;
+
+	entry = lut->data;
+	for (i = 0; i < drm_color_lut_32_size(lut); i++) {
+		if (tests & DRM_COLOR_LUT_EQUAL_CHANNELS) {
+			if (entry[i].red != entry[i].blue ||
+			    entry[i].red != entry[i].green) {
+				DRM_DEBUG_KMS("All LUT entries must have equal r/g/b\n");
+				return -EINVAL;
+			}
+		}
+
+		if (i > 0 && tests & DRM_COLOR_LUT_NON_DECREASING) {
+			if (entry[i].red < entry[i - 1].red ||
+			    entry[i].green < entry[i - 1].green ||
+			    entry[i].blue < entry[i - 1].blue) {
+				DRM_DEBUG_KMS("LUT entries must never decrease.\n");
+				return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_color_lut_32_check);
diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
index ed81741036d7..882253a82bf1 100644
--- a/include/drm/drm_color_mgmt.h
+++ b/include/drm/drm_color_mgmt.h
@@ -72,6 +72,18 @@ static inline int drm_color_lut_size(const struct drm_property_blob *blob)
 	return blob->length / sizeof(struct drm_color_lut);
 }
 
+/**
+ * drm_color_lut_32_size - calculate the number of entries in the extended LUT
+ * @blob: blob containing the LUT
+ *
+ * Returns:
+ * The number of entries in the color LUT stored in @blob.
+ */
+static inline int drm_color_lut_32_size(const struct drm_property_blob *blob)
+{
+	return blob->length / sizeof(struct drm_color_lut_32);
+}
+
 enum drm_color_encoding {
 	DRM_COLOR_YCBCR_BT601,
 	DRM_COLOR_YCBCR_BT709,
@@ -118,4 +130,5 @@ enum drm_color_lut_tests {
 };
 
 int drm_color_lut_check(const struct drm_property_blob *lut, u32 tests);
+int drm_color_lut_32_check(const struct drm_property_blob *lut, u32 tests);
 #endif
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index a4a7ab689631..e5090416c1ae 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -872,6 +872,23 @@ struct drm_color_lut {
 	__u16 reserved;
 };
 
+/**
+ * struct drm_color_lut_32 - Represents high precision lut values
+ *
+ * Creating 32 bit palette entries for better data
+ * precision. This will be required for HDR and
+ * similar color processing usecases.
+ */
+struct drm_color_lut_32 {
+	/*
+	 * Data for high precision LUTs
+	 */
+	__u32 red;
+	__u32 green;
+	__u32 blue;
+	__u32 reserved;
+};
+
 /**
  * enum drm_colorop_type - Type of color operation
  *
@@ -879,6 +896,7 @@ struct drm_color_lut {
  * and defines a different set of properties. This enum defines all types and
  * gives a high-level description.
  */
+
 enum drm_colorop_type {
 	/**
 	 * @DRM_COLOROP_1D_CURVE:
-- 
2.42.0