[RFC 02/13] drm/edid: Parse MAX_FRL field from HFVSDB block

[Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>]

From: Swati Sharma <swati2.sharma@xxxxxxxxx>

This patch parses MAX_FRL field to get the MAX rate in Gbps that
the HDMI 2.1 panel can support in FRL mode. Source need this
field to determine the optimal rate between the source and sink
during FRL training.

Signed-off-by: Sharma, Swati2 <swati2.sharma@xxxxxxxxx>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
---
 drivers/gpu/drm/drm_edid.c  | 51 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h |  6 +++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 631125b46e04..8afb136e73f5 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4849,6 +4849,52 @@ static void drm_parse_vcdb(struct drm_connector *connector, const u8 *db)
 		info->rgb_quant_range_selectable = true;
 }
 
+static
+void drm_get_max_frl_rate(int max_frl_rate, u8 *max_lanes, u8 *max_rate_per_lane)
+{
+	switch(max_frl_rate) {
+	case 1:
+		*max_lanes = 3;
+		*max_rate_per_lane = 3;
+		break;
+	case 2:
+		*max_lanes = 3;
+		*max_rate_per_lane = 6;
+		break;
+	case 3:
+		*max_lanes = 4;
+		*max_rate_per_lane = 6;
+		break;
+	case 4:
+		*max_lanes = 4;
+		*max_rate_per_lane = 8;
+		break;
+	case 5:
+		*max_lanes = 4;
+		*max_rate_per_lane = 10;
+		break;
+	case 6:
+		*max_lanes = 4;
+		*max_rate_per_lane = 12;
+		break;
+	case 0:
+	default:
+		*max_lanes = 0;
+		*max_rate_per_lane = 0;
+	}
+}
+
+static void drm_parse_hdmi_21_additional_fields(struct drm_connector *connector,
+						const u8 *db)
+{
+	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
+	u8 max_frl_rate;
+
+	max_frl_rate = db[7] & DRM_EDID_MAX_FRL_RATE_MASK;
+	drm_get_max_frl_rate(max_frl_rate, &hdmi->max_lanes,
+			     &hdmi->max_frl_rate_per_lane);
+}
+
 static void drm_parse_ycbcr420_deep_color_info(struct drm_connector *connector,
 					       const u8 *db)
 {
@@ -4902,6 +4948,11 @@ static void drm_parse_hdmi_forum_vsdb(struct drm_connector *connector,
 		}
 	}
 
+	if (hf_vsdb[7]) {
+		    DRM_DEBUG_KMS("hdmi_21 sink detected. parsing edid\n");
+		    drm_parse_hdmi_21_additional_fields(connector, hf_vsdb);
+	}
+
 	drm_parse_ycbcr420_deep_color_info(connector, hf_vsdb);
 }
 
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 928136556174..f351bf10c076 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -207,6 +207,12 @@ struct drm_hdmi_info {
 
 	/** @y420_dc_modes: bitmap of deep color support index */
 	u8 y420_dc_modes;
+
+	/** @max_frl_rate_per_lane: support fixed rate link */
+	u8 max_frl_rate_per_lane;
+
+	/** @max_lanes: supported by sink */
+	u8 max_lanes;
 };
 
 /**
-- 
2.17.1

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