[v4 5/5] drm/edid: check for HF-SCDB block

[Lee Shawn C]

Find HF-SCDB information in CEA extensions block. And retrieve
Max_TMDS_Character_Rate that support by sink device.

Cc: Jani Nikula <jani.nik...@linux.intel.com>
Cc: Ville Syrjala <ville.syrj...@linux.intel.com>
Cc: Ankit Nautiyal <ankit.k.nauti...@intel.com>
Signed-off-by: Lee Shawn C <shawn.c....@intel.com>
---
 drivers/gpu/drm/drm_edid.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 2b8ddc956ce2..d6b48c543c23 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3350,6 +3350,7 @@ add_detailed_modes(struct drm_connector *connector, 
struct edid *edid,
 #define EXT_VIDEO_DATA_BLOCK_420       0x0E
 #define EXT_VIDEO_CAP_BLOCK_Y420CMDB   0x0F
 #define EXT_VIDEO_HF_EEODB_DATA_BLOCK  0x78
+#define EXT_VIDEO_HF_SCDB_DATA_BLOCK   0x79
 #define EDID_BASIC_AUDIO       (1 << 6)
 #define EDID_CEA_YCRCB444      (1 << 5)
 #define EDID_CEA_YCRCB422      (1 << 4)
@@ -4277,6 +4278,20 @@ static bool cea_db_is_vcdb(const u8 *db)
        return true;
 }
 
+static bool cea_db_is_hf_scdb(const u8 *db)
+{
+       if (cea_db_tag(db) != USE_EXTENDED_TAG)
+               return false;
+
+       if (cea_db_payload_len(db) < 7)
+               return false;
+
+       if (cea_db_extended_tag(db) != EXT_VIDEO_HF_SCDB_DATA_BLOCK)
+               return false;
+
+       return true;
+}
+
 static bool cea_db_is_y420cmdb(const u8 *db)
 {
        if (cea_db_tag(db) != USE_EXTENDED_TAG)
@@ -4987,6 +5002,25 @@ static void drm_parse_vcdb(struct drm_connector 
*connector, const u8 *db)
                info->rgb_quant_range_selectable = true;
 }
 
+static void drm_parse_hf_scdb(struct drm_connector *connector, const u8 *db)
+{
+       struct drm_display_info *info = &connector->display_info;
+       u32 max_tmds_clock;
+
+       DRM_DEBUG_KMS("HF-SCDB version 0x%02x\n", db[4]);
+
+       max_tmds_clock = db[5] * 5000;
+       if (info->max_tmds_clock < max_tmds_clock) {
+               info->max_tmds_clock = max_tmds_clock;
+               DRM_DEBUG_KMS("HF-SCDB: max TMDS clock %d kHz\n",
+                             info->max_tmds_clock);
+       }
+
+       /*
+        * ToDo: Parse the remaining SCDB data if needed
+        */
+}
+
 static
 void drm_get_max_frl_rate(int max_frl_rate, u8 *max_lanes, u8 
*max_rate_per_lane)
 {
@@ -5282,6 +5316,8 @@ 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_hf_scdb(db))
+                       drm_parse_hf_scdb(connector, db);
                if (cea_db_is_hdmi_hdr_metadata_block(db))
                        drm_parse_hdr_metadata_block(connector, db);
        }
-- 
2.17.1