[PATCH 3/6] drm/edid: detect SCDC support in HF-VSDB

[Shashank Sharma]

This patch does following:
- Adds a new structure (drm_hdmi_info) in drm_display_info.
  This structure will be used to save and indicate if sink
  supports advance HDMI 2.0 features
- Checks the HF-VSDB block for presence of SCDC, and marks it
  in hdmi_info structure.
- If SCDC is present, checks if sink is capable of generating
  scdc read request, and marks it in hdmi_info structure.

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
---
 drivers/gpu/drm/drm_edid.c  | 14 ++++++++++++++
 include/drm/drm_connector.h | 26 ++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 96d3e47..37902e5 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3802,6 +3802,18 @@ enum hdmi_quantization_range
 }
 EXPORT_SYMBOL(drm_default_rgb_quant_range);
 
+static void drm_detect_hdmi_scdc(struct drm_connector *connector,
+				 const u8 *hf_vsdb)
+{
+	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi_info;
+
+	if (hf_vsdb[6] & 0x80) {
+		hdmi->scdc_supported = true;
+		if (hf_vsdb[6] & 0x40)
+			hdmi->scdc_rr = true;
+	}
+}
+
 static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
 					   const u8 *hdmi)
 {
@@ -3916,6 +3928,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
 
 		if (cea_db_is_hdmi_vsdb(db))
 			drm_parse_hdmi_vsdb_video(connector, db);
+		if (cea_db_is_hdmi_forum_vsdb(db))
+			drm_detect_hdmi_scdc(connector, db);
 	}
 }
 
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index e5e1edd..2435598 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -87,6 +87,27 @@ enum subpixel_order {
 	SubPixelVerticalRGB,
 	SubPixelVerticalBGR,
 	SubPixelNone,
+
+};
+
+/**
+ * struct drm_hdmi_info - runtime data about the connected sink
+ *
+ * Describes if a given hdmi display supports advance HDMI 2.0 featutes.
+ * This information is available in CEA-861-F extension blocks (like
+ * HF-VSDB)
+ * For sinks which provide an EDID this can be filled out by calling
+ * drm_add_edid_modes().
+ */
+struct drm_hdmi_info {
+	/**
+	 * @scdc_supported: status control & data channel present.
+	 */
+	bool scdc_supported;
+	/**
+	 * @scdc_rr: sink is capable of generating scdc read request.
+	 */
+	bool scdc_rr;
 };
 
 /**
@@ -188,6 +209,11 @@ struct drm_display_info {
 	 * @cea_rev: CEA revision of the HDMI sink.
 	 */
 	u8 cea_rev;
+
+	/**
+	 * @hdmi_info: advance features of a HDMI sink.
+	 */
+	struct drm_hdmi_info hdmi_info;
 };
 
 int drm_display_info_set_bus_formats(struct drm_display_info *info,
-- 
1.9.1