drm: Add Enhanced LUT precision structure

Existing LUT precision structure drm_color_lut has 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: Alex Hung <alex.hung@amd.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Sebastian Wick <sebastian.wick@redhat.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patch.msgid.link/20251115000237.3561250-36-alex.hung@amd.com

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
index 131c1c9ae92f..c598b99673fc 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -874,3 +874,46 @@ void drm_crtc_fill_palette_8(struct drm_crtc *crtc, drm_crtc_set_lut_func set_pa
 		fill_palette_8(crtc, i, set_palette);
 }
 EXPORT_SYMBOL(drm_crtc_fill_palette_8);
+
+/**
+ * drm_color_lut32_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_lut32_check(const struct drm_property_blob *lut, u32 tests)
+{
+	const struct drm_color_lut32 *entry;
+	int i;
+
+	if (!lut || !tests)
+		return 0;
+
+	entry = lut->data;
+	for (i = 0; i < drm_color_lut32_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_lut32_check);