[PATCH 3/5] drm: Add drm_connector_state_select_rgb_quantization_range() helper

[Yussuf Khalil]

This helper can be used to determine the appropriate RGB quantization range
based on a connector's "RGB quantization range" property and a mode.

Signed-off-by: Yussuf Khalil <dev at pp3345.net>
---
 drivers/gpu/drm/drm_connector.c | 31 +++++++++++++++++++++++++++++++
 include/drm/drm_connector.h     |  4 ++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index e60d3b6e5e56..d5a46bbf284e 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2187,6 +2187,37 @@ int drm_connector_set_panel_orientation_with_quirk(
 }
 EXPORT_SYMBOL(drm_connector_set_panel_orientation_with_quirk);
 
+/**
+ * drm_connector_state_select_rgb_quantization_range - find RGB quantization
+ * range appropriate for a connector's state and mode
+ *
+ * @state: state of the connector for which to determine the range
+ * @mode: mode for which to determine the range
+ *
+ * For a given connector state (i.e., RGB quantization range property) and a
+ * given mode, determine which RGB quantization range should be used.
+ *
+ * Returns:
+ * A constant from the HDMI quantization range enum.
+ */
+enum hdmi_quantization_range drm_connector_state_select_rgb_quantization_range(
+	const struct drm_connector_state *state,
+        const struct drm_display_mode *mode)
+{
+	switch (state->rgb_quantization_range) {
+	default:
+		WARN_ON(1);
+		/* fallthrough */
+	case DRM_MODE_RGB_QUANTIZATION_RANGE_AUTOMATIC:
+		return drm_default_rgb_quant_range(mode);
+	case DRM_MODE_RGB_QUANTIZATION_RANGE_FULL:
+		return HDMI_QUANTIZATION_RANGE_FULL;
+	case DRM_MODE_RGB_QUANTIZATION_RANGE_LIMITED:
+		return HDMI_QUANTIZATION_RANGE_LIMITED;
+	}
+}
+EXPORT_SYMBOL(drm_connector_state_select_rgb_quantization_range);
+
 int drm_connector_set_obj_prop(struct drm_mode_object *obj,
 				    struct drm_property *property,
 				    uint64_t value)
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index f605e0fbcc0e..43ce305d882f 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -42,6 +42,7 @@ struct drm_property_blob;
 struct drm_printer;
 struct edid;
 struct i2c_adapter;
+struct drm_display_mode;
 
 enum drm_connector_force {
 	DRM_FORCE_UNSPECIFIED,
@@ -1621,6 +1622,9 @@ int drm_connector_set_panel_orientation_with_quirk(
 	int width, int height);
 int drm_connector_attach_max_bpc_property(struct drm_connector *connector,
 					  int min, int max);
+enum hdmi_quantization_range drm_connector_state_select_rgb_quantization_range(
+	const struct drm_connector_state *state,
+	const struct drm_display_mode *mode);
 
 /**
  * struct drm_tile_group - Tile group metadata
-- 
2.26.0