[PATCH 06/28] 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>
---
 include/drm/drm_color_mgmt.h | 23 +++++++++++++++++++++++
 include/uapi/drm/drm_mode.h  | 17 +++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
index ed81741036d7..72a08b5f7d14 100644
--- a/include/drm/drm_color_mgmt.h
+++ b/include/drm/drm_color_mgmt.h
@@ -50,6 +50,29 @@ static inline u32 drm_color_lut_extract(u32 user_input, int bit_precision)
 					 (1 << 16) - 1);
 }
 
+/* TODO: Add uapi documentation
+ * Added to accommodate enhanced LUT precision.
+ * Max LUT precision is 32 bits.
+ */
+static inline u64 drm_color_lut_extract_ext(u64 user_input, u32 bit_precision)
+{
+	u64 val = user_input & 0xffffffff;
+	u32 max;
+
+	if (bit_precision > 32)
+		return 0;
+
+	max = 0xffffffff >> (32 - bit_precision);
+	/* Round only if we're not using full precision. */
+	if (bit_precision < 32) {
+		val += 1UL << (32 - bit_precision - 1);
+		val >>= 32 - bit_precision;
+	}
+
+	return ((user_input & 0xffffffff00000000) |
+		clamp_val(val, 0, max));
+}
+
 u64 drm_color_ctm_s31_32_to_qm_n(u64 user_input, u32 m, u32 n);
 
 void drm_crtc_enable_color_mgmt(struct drm_crtc *crtc,
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 68696253867e..bbc5be97c80f 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -866,6 +866,23 @@ struct drm_color_lut {
 	__u16 reserved;
 };
 
+/**
+ * struct drm_color_lut_ext - Represents high precision lut values
+ *
+ * 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;
+};
+
 enum drm_colorop_type {
 	DRM_COLOROP_1D_CURVE,
 	DRM_COLOROP_CTM_3X3,
-- 
2.42.0