drm/i915: Add state readout for DRM infoframe

Added state readout for DRM infoframe and enabled
state validation for DRM infoframe.

v2: Addressed Ville's review comments and dropped the
unused drm infoframe read at intel_hdmi_init.

v3: Removed a redundant platform check as per Ville's
comment.
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1558015817-12025-13-git-send-email-uma.shankar@intel.com

drivers/gpu/drm/i915/intel_ddi.c

@@ -3844,6 +3844,9 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
 	intel_read_infoframe(encoder, pipe_config,
 			     HDMI_INFOFRAME_TYPE_VENDOR,
 			     &pipe_config->infoframes.hdmi);
+	intel_read_infoframe(encoder, pipe_config,
+			     HDMI_INFOFRAME_TYPE_DRM,
+			     &pipe_config->infoframes.drm);
 }
 
 static enum intel_output_type

drivers/gpu/drm/i915/intel_display.c

@@ -12569,6 +12569,7 @@ intel_pipe_config_compare(struct drm_i915_private *dev_priv,
 	PIPE_CONF_CHECK_INFOFRAME(avi);
 	PIPE_CONF_CHECK_INFOFRAME(spd);
 	PIPE_CONF_CHECK_INFOFRAME(hdmi);
+	PIPE_CONF_CHECK_INFOFRAME(drm);
 
 #undef PIPE_CONF_CHECK_X
 #undef PIPE_CONF_CHECK_I