drm/i915: Never set limited_color_range=true for YCbCr output

crtc_state->limited_color_range only applies to RGB output but
we're currently setting it even for YCbCr output. That will
lead to conflicting MSA and PIPECONF settings which can mess
up the image. Let's make sure limited_color_range stays unset
with YCbCr output.

Also WARN if we end up with such a bogus combination when
programming the MSA MISC bits as it's impossible to even
indicate quantization rangle for YCbCr via MSA MISC. YCbCr
output is simply assumed to be limited range always. Note
that VSC SDP does provide a mechanism for full range YCbCr,
so in the future we may want to rethink how we compute/store
this state.

And for good measure we add the same WARN to the HDMI path.

v2: s/==/!=/ in the HDMI WARN
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190718164523.11738-1-ville.syrjala@linux.intel.comReviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -1706,9 +1706,6 @@ void intel_ddi_set_pipe_settings(const struct intel_crtc_state *crtc_state)
 
 	temp = TRANS_MSA_SYNC_CLK;
 
-	if (crtc_state->limited_color_range)
-		temp |= TRANS_MSA_CEA_RANGE;
-
 	switch (crtc_state->pipe_bpp) {
 	case 18:
 		temp |= TRANS_MSA_6_BPC;
@@ -1727,6 +1724,13 @@ void intel_ddi_set_pipe_settings(const struct intel_crtc_state *crtc_state)
 		break;
 	}
 
+	/* nonsense combination */
+	WARN_ON(crtc_state->limited_color_range &&
+		crtc_state->output_format != INTEL_OUTPUT_FORMAT_RGB);
+
+	if (crtc_state->limited_color_range)
+		temp |= TRANS_MSA_CEA_RANGE;
+
 	/*
 	 * As per DP 1.2 spec section 2.3.4.3 while sending
 	 * YCBCR 444 signals we should program MSA MISC1/0 fields with

drivers/gpu/drm/i915/display/intel_dp.c

@@ -2150,6 +2150,16 @@ bool intel_dp_limited_color_range(const struct intel_crtc_state *crtc_state,
 	const struct drm_display_mode *adjusted_mode =
 		&crtc_state->base.adjusted_mode;
 
+	/*
+	 * Our YCbCr output is always limited range.
+	 * crtc_state->limited_color_range only applies to RGB,
+	 * and it must never be set for YCbCr or we risk setting
+	 * some conflicting bits in PIPECONF which will mess up
+	 * the colors on the monitor.
+	 */
+	if (crtc_state->output_format != INTEL_OUTPUT_FORMAT_RGB)
+		return false;
+
 	if (intel_conn_state->broadcast_rgb == INTEL_BROADCAST_RGB_AUTO) {
 		/*
 		 * See:

drivers/gpu/drm/i915/display/intel_hdmi.c

@@ -724,6 +724,10 @@ intel_hdmi_compute_avi_infoframe(struct intel_encoder *encoder,
 
 	drm_hdmi_avi_infoframe_colorspace(frame, conn_state);
 
+	/* nonsense combination */
+	WARN_ON(crtc_state->limited_color_range &&
+		crtc_state->output_format != INTEL_OUTPUT_FORMAT_RGB);
+
 	if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_RGB) {
 		drm_hdmi_avi_infoframe_quant_range(frame, connector,
 						   adjusted_mode,
@@ -2373,6 +2377,16 @@ static bool intel_hdmi_limited_color_range(const struct intel_crtc_state *crtc_s
 	const struct drm_display_mode *adjusted_mode =
 		&crtc_state->base.adjusted_mode;
 
+	/*
+	 * Our YCbCr output is always limited range.
+	 * crtc_state->limited_color_range only applies to RGB,
+	 * and it must never be set for YCbCr or we risk setting
+	 * some conflicting bits in PIPECONF which will mess up
+	 * the colors on the monitor.
+	 */
+	if (crtc_state->output_format != INTEL_OUTPUT_FORMAT_RGB)
+		return false;
+
 	if (intel_conn_state->broadcast_rgb == INTEL_BROADCAST_RGB_AUTO) {
 		/* See CEA-861-E - 5.1 Default Encoding Parameters */
 		return crtc_state->has_hdmi_sink &&
@@ -2406,9 +2420,6 @@ int intel_hdmi_compute_config(struct intel_encoder *encoder,
 	if (pipe_config->has_hdmi_sink)
 		pipe_config->has_infoframe = true;
 
-	pipe_config->limited_color_range =
-		intel_hdmi_limited_color_range(pipe_config, conn_state);
-
 	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
 		pipe_config->pixel_multiplier = 2;
 
@@ -2419,6 +2430,9 @@ int intel_hdmi_compute_config(struct intel_encoder *encoder,
 		}
 	}
 
+	pipe_config->limited_color_range =
+		intel_hdmi_limited_color_range(pipe_config, conn_state);
+
 	if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv))
 		pipe_config->has_pch_encoder = true;