[PATCH v4 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 advanced HDMI 2.0 features
- Adds another structure drm_scdc within drm_hdmi_info, to
  reflect scdc support and capabilities in connected HDMI 2.0 sink.
- Checks the HF-VSDB block for presence of SCDC, and marks it
  in scdc structure
- If SCDC is present, checks if sink is capable of generating
  SCDC read request, and marks it in scdc structure.

V2: Addressed review comments
 Thierry:
 - Fix typos in commit message and make abbreviation consistent
   across the commit message.
 - Change structure object name from hdmi_info -> hdmi
 - Fix typos and abbreviations in description of structure drm_hdmi_info
   end the description with a full stop.
 - Create a structure drm_scdc, and keep all information related to SCDC
   register set (supported, read request supported) etc in it.

 Ville:
 - Change rr -> read_request
 - Call drm_detect_scrambling function drm_parse_hf_vsdb so that all
   of HF-VSDB parsing can be kept in same function, in incremental
   patches.

V3: Rebase.
V4: Rebase.

Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
Reviewed-by: Thierry Reding <treding at nvidia.com>
---
 drivers/gpu/drm/drm_edid.c  | 14 ++++++++++++++
 include/drm/drm_connector.h | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 8acdd08..63b79be 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3808,6 +3808,18 @@ enum hdmi_quantization_range
 }
 EXPORT_SYMBOL(drm_default_rgb_quant_range);
 
+static void drm_parse_hdmi_forum_vsdb(struct drm_connector *connector,
+				 const u8 *hf_vsdb)
+{
+	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
+
+	if (hf_vsdb[6] & 0x80) {
+		hdmi->scdc.supported = true;
+		if (hf_vsdb[6] & 0x40)
+			hdmi->scdc.read_request = true;
+	}
+}
+
 static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
 					   const u8 *hdmi)
 {
@@ -3922,6 +3934,8 @@ 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_parse_hdmi_forum_vsdb(connector, db);
 	}
 }
 
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index e5e1edd..6d5304e 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -87,6 +87,34 @@ enum subpixel_order {
 	SubPixelVerticalRGB,
 	SubPixelVerticalBGR,
 	SubPixelNone,
+
+};
+
+/*
+ * struct drm_scdc - Information about scdc capabilities of a HDMI 2.0 sink
+ *
+ * Provides SCDC register support and capabilities related information on a
+ * HDMI 2.0 sink. In case of a HDMI 1.4 sink, all parameter must be 0.
+ */
+struct drm_scdc {
+	/**
+	 * @supported: status control & data channel present.
+	 */
+	bool supported;
+	/**
+	 * @read_request: sink is capable of generating scdc read request.
+	 */
+	bool read_request;
+};
+
+/**
+ * struct drm_hdmi_info - runtime information about the connected HDMI sink
+ *
+ * Describes if a given display supports advanced HDMI 2.0 features.
+ * This information is available in CEA-861-F extension blocks (like HF-VSDB).
+ */
+struct drm_hdmi_info {
+	struct drm_scdc scdc;
 };
 
 /**
@@ -188,6 +216,11 @@ struct drm_display_info {
 	 * @cea_rev: CEA revision of the HDMI sink.
 	 */
 	u8 cea_rev;
+
+	/**
+	 * @hdmi: advance features of a HDMI sink.
+	 */
+	struct drm_hdmi_info hdmi;
 };
 
 int drm_display_info_set_bus_formats(struct drm_display_info *info,
-- 
1.9.1