drm: Parse HDR metadata info from EDID

HDR metadata block is introduced in CEA-861.3 spec.
Parsing the same to get the panel's HDR metadata.

v2: Rebase and added Ville's POC changes to the patch.

v3: No Change

v4: Addressed Shashank's review comments

v5: Addressed Shashank's comment and added his RB.

v6: Addressed Jonas Karlman review comments.

v7: Adressed Ville's review comments and fixed the issue
with length handling.

v8: Put the length check as per the convention followed in
existing code, as suggested by Ville.

Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1558015817-12025-4-git-send-email-uma.shankar@intel.com

drivers/gpu/drm/drm_edid.c

@@ -2852,6 +2852,7 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid,
 #define VIDEO_BLOCK     0x02
 #define VENDOR_BLOCK    0x03
 #define SPEAKER_BLOCK	0x04
+#define HDR_STATIC_METADATA_BLOCK	0x6
 #define USE_EXTENDED_TAG 0x07
 #define EXT_VIDEO_CAPABILITY_BLOCK 0x00
 #define EXT_VIDEO_DATA_BLOCK_420	0x0E
@@ -3834,6 +3835,54 @@ static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
 	mode->clock = clock;
 }
 
+static bool cea_db_is_hdmi_hdr_metadata_block(const u8 *db)
+{
+	if (cea_db_tag(db) != USE_EXTENDED_TAG)
+		return false;
+
+	if (db[1] != HDR_STATIC_METADATA_BLOCK)
+		return false;
+
+	if (cea_db_payload_len(db) < 3)
+		return false;
+
+	return true;
+}
+
+static uint8_t eotf_supported(const u8 *edid_ext)
+{
+	return edid_ext[2] &
+		(BIT(HDMI_EOTF_TRADITIONAL_GAMMA_SDR) |
+		 BIT(HDMI_EOTF_TRADITIONAL_GAMMA_HDR) |
+		 BIT(HDMI_EOTF_SMPTE_ST2084));
+}
+
+static uint8_t hdr_metadata_type(const u8 *edid_ext)
+{
+	return edid_ext[3] &
+		BIT(HDMI_STATIC_METADATA_TYPE1);
+}
+
+static void
+drm_parse_hdr_metadata_block(struct drm_connector *connector, const u8 *db)
+{
+	u16 len;
+
+	len = cea_db_payload_len(db);
+
+	connector->hdr_sink_metadata.hdmi_type1.eotf =
+						eotf_supported(db);
+	connector->hdr_sink_metadata.hdmi_type1.metadata_type =
+						hdr_metadata_type(db);
+
+	if (len >= 4)
+		connector->hdr_sink_metadata.hdmi_type1.max_cll = db[4];
+	if (len >= 5)
+		connector->hdr_sink_metadata.hdmi_type1.max_fall = db[5];
+	if (len >= 6)
+		connector->hdr_sink_metadata.hdmi_type1.min_cll = db[6];
+}
+
 static void
 drm_parse_hdmi_vsdb_audio(struct drm_connector *connector, const u8 *db)
 {
@@ -4461,6 +4510,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 			drm_parse_y420cmdb_bitmap(connector, db);
 		if (cea_db_is_vcdb(db))
 			drm_parse_vcdb(connector, db);
+		if (cea_db_is_hdmi_hdr_metadata_block(db))
+			drm_parse_hdr_metadata_block(connector, db);
 	}
 }