drm/connector: hdmi: Add RGB Quantization Range to the connector state

HDMI controller drivers will need to figure out the RGB range they need
to configure based on a mode and property values. Let's expose that in
the HDMI connector state so drivers can just use that value.

Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240527-kms-hdmi-connector-state-v15-20-c5af16c3aae2@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>

drivers/gpu/drm/display/drm_hdmi_state_helper.c

@@ -51,6 +51,33 @@ connector_state_get_mode(const struct drm_connector_state *conn_state)
 	return &crtc_state->mode;
 }
 
+static bool hdmi_is_limited_range(const struct drm_connector *connector,
+				  const struct drm_connector_state *conn_state)
+{
+	const struct drm_display_info *info = &connector->display_info;
+	const struct drm_display_mode *mode =
+		connector_state_get_mode(conn_state);
+
+	/*
+	 * The Broadcast RGB property only applies to RGB format, and
+	 * i915 just assumes limited range for YCbCr output, so let's
+	 * just do the same.
+	 */
+	if (conn_state->hdmi.output_format != HDMI_COLORSPACE_RGB)
+		return true;
+
+	if (conn_state->hdmi.broadcast_rgb == DRM_HDMI_BROADCAST_RGB_FULL)
+		return false;
+
+	if (conn_state->hdmi.broadcast_rgb == DRM_HDMI_BROADCAST_RGB_LIMITED)
+		return true;
+
+	if (!info->is_hdmi)
+		return false;
+
+	return drm_default_rgb_quant_range(mode) == HDMI_QUANTIZATION_RANGE_LIMITED;
+}
+
 static bool
 sink_supports_format_bpc(const struct drm_connector *connector,
 			 const struct drm_display_info *info,
@@ -329,6 +356,8 @@ int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
 		connector_state_get_mode(new_conn_state);
 	int ret;
 
+	new_conn_state->hdmi.is_limited_range = hdmi_is_limited_range(connector, new_conn_state);
+
 	ret = hdmi_compute_config(connector, new_conn_state, mode);
 	if (ret)
 		return ret;

drivers/gpu/drm/drm_atomic.c

@@ -1147,6 +1147,7 @@ static void drm_atomic_connector_print_state(struct drm_printer *p,
 	    connector->connector_type == DRM_MODE_CONNECTOR_HDMIB) {
 		drm_printf(p, "\tbroadcast_rgb=%s\n",
 			   drm_hdmi_connector_get_broadcast_rgb_name(state->hdmi.broadcast_rgb));
+		drm_printf(p, "\tis_limited_range=%c\n", state->hdmi.is_limited_range ? 'y' : 'n');
 		drm_printf(p, "\toutput_bpc=%u\n", state->hdmi.output_bpc);
 		drm_printf(p, "\toutput_format=%s\n",
 			   drm_hdmi_connector_get_output_format_name(state->hdmi.output_format));

include/drm/drm_connector.h

@@ -1070,6 +1070,12 @@ struct drm_connector_state {
 		 */
 		enum drm_hdmi_broadcast_rgb broadcast_rgb;
 
+		/**
+		 * @is_full_range: Is the output supposed to use a full
+		 * RGB Quantization Range or not?
+		 */
+		bool is_limited_range;
+
 		/**
 		 * @output_bpc: Bits per color channel to output.
 		 */