[RFC v2 02/22] drm: Add Enhanced Gamma and color lut range attributes

[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.

This also defines a new structure to define color lut ranges,
along with related macro definitions and enums. This will help
describe multi segmented lut ranges in the hardware.

Signed-off-by: Uma Shankar <uma.shankar at intel.com>
---
 include/uapi/drm/drm_mode.h | 58 +++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 90c55383f1ee..1079794c86c3 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -903,6 +903,64 @@ struct hdr_output_metadata {
 	};
 };
 
+/*
+ * DRM_MODE_LUT_GAMMA|DRM_MODE_LUT_DEGAMMA is legal and means the LUT
+ * can be used for either purpose, but not simultaneously. To expose
+ * modes that support gamma and degamma simultaneously the gamma mode
+ * must declare distinct DRM_MODE_LUT_GAMMA and DRM_MODE_LUT_DEGAMMA
+ * ranges.
+ */
+/* LUT is for gamma (after CTM) */
+#define DRM_MODE_LUT_GAMMA BIT(0)
+/* LUT is for degamma (before CTM) */
+#define DRM_MODE_LUT_DEGAMMA BIT(1)
+/* linearly interpolate between the points */
+#define DRM_MODE_LUT_INTERPOLATE BIT(2)
+/*
+ * the last value of the previous range is the
+ * first value of the current range.
+ */
+#define DRM_MODE_LUT_REUSE_LAST BIT(3)
+/* the curve must be non-decreasing */
+#define DRM_MODE_LUT_NON_DECREASING BIT(4)
+/* the curve is reflected across origin for negative inputs */
+#define DRM_MODE_LUT_REFLECT_NEGATIVE BIT(5)
+/* the same curve (red) is used for blue and green channels as well */
+#define DRM_MODE_LUT_SINGLE_CHANNEL BIT(6)
+
+struct drm_color_lut_range {
+	/* DRM_MODE_LUT_* */
+	__u32 flags;
+	/* number of points on the curve */
+	__u16 count;
+	/* input/output bits per component */
+	__u8 input_bpc, output_bpc;
+	/* input start/end values */
+	__s32 start, end;
+	/* output min/max values */
+	__s32 min, max;
+};
+
+enum lut_type {
+	LUT_TYPE_DEGAMMA = 0,
+	LUT_TYPE_GAMMA = 1,
+};
+
+/*
+ * Creating 64 bit palette entries for better data
+ * precision. This will be required for HDR and
+ * similar color processing usecases.
+ */
+struct drm_color_lut_ext {
+	/*
+	 * Data is U32.32 fixed point format.
+	 */
+	__u64 red;
+	__u64 green;
+	__u64 blue;
+	__u64 reserved;
+};
+
 #define DRM_MODE_PAGE_FLIP_EVENT 0x01
 #define DRM_MODE_PAGE_FLIP_ASYNC 0x02
 #define DRM_MODE_PAGE_FLIP_TARGET_ABSOLUTE 0x4
-- 
2.26.2