drm/i915/display: Implement DRM infoframe read for LSPCON

Implement Read back of HDR metadata infoframes i.e Dynamic Range
and Mastering Infoframe for LSPCON devices.

v2: Added proper bitmask of enabled infoframes as per Ville's
recommendation.

v3: Dropped a redundant wrapper as per Ville's comment.

v4: Dropped a redundant print, added Ville's RB.
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201130204738.2443-14-uma.shankar@intel.com

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

@@ -555,10 +555,9 @@ void hsw_write_infoframe(struct intel_encoder *encoder,
 	intel_de_posting_read(dev_priv, ctl_reg);
 }
 
-static void hsw_read_infoframe(struct intel_encoder *encoder,
-			       const struct intel_crtc_state *crtc_state,
-			       unsigned int type,
-			       void *frame, ssize_t len)
+void hsw_read_infoframe(struct intel_encoder *encoder,
+			const struct intel_crtc_state *crtc_state,
+			unsigned int type, void *frame, ssize_t len)
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;

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

@@ -484,7 +484,10 @@ void lspcon_read_infoframe(struct intel_encoder *encoder,
 			   unsigned int type,
 			   void *frame, ssize_t len)
 {
-	/* FIXME implement this */
+	/* FIXME implement for AVI Infoframe as well */
+	if (type == HDMI_PACKET_TYPE_GAMUT_METADATA)
+		hsw_read_infoframe(encoder, crtc_state, type,
+				   frame, len);
 }
 
 void lspcon_set_infoframes(struct intel_encoder *encoder,

drivers/gpu/drm/i915/display/intel_lspcon.h

@@ -39,5 +39,9 @@ void hsw_write_infoframe(struct intel_encoder *encoder,
 			 const struct intel_crtc_state *crtc_state,
 			 unsigned int type,
 			 const void *frame, ssize_t len);
+void hsw_read_infoframe(struct intel_encoder *encoder,
+			const struct intel_crtc_state *crtc_state,
+			unsigned int type,
+			void *frame, ssize_t len);
 
 #endif /* __INTEL_LSPCON_H__ */