drm/amd/display: Add Freesync HDMI support to DM

[Why]
Add necessary support for Freesync HDMI in Linux DM

[How]
- Support Freesync HDMI by calling DC interace
- Report Freesync capability to vrr_range debugfs from DRM
- Depends on coming DMCU/DMUB firmware to enable feature
Signed-off-by: Stylon Wang <stylon.wang@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <Qingqing.Zhuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -34,6 +34,7 @@
 #include "dc/inc/hw/dmcu.h"
 #include "dc/inc/hw/abm.h"
 #include "dc/dc_dmub_srv.h"
+#include "dc/dc_edid_parser.h"
 #include "amdgpu_dm_trace.h"
 
 #include "vid.h"
@@ -6908,6 +6909,12 @@ static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
 		 */
 		drm_mode_sort(&connector->probed_modes);
 		amdgpu_dm_get_native_mode(connector);
+
+		/* Freesync capabilities are reset by calling
+		 * drm_add_edid_modes() and need to be
+		 * restored here.
+		 */
+		amdgpu_dm_update_freesync_caps(connector, edid);
 	} else {
 		amdgpu_dm_connector->num_modes = 0;
 	}
@@ -9627,11 +9634,84 @@ static bool is_dp_capable_without_timing_msa(struct dc *dc,
 
 	return capable;
 }
+
+static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector,
+		uint8_t *edid_ext, int len,
+		struct amdgpu_hdmi_vsdb_info *vsdb_info)
+{
+	int i;
+	struct amdgpu_device *adev = drm_to_adev(aconnector->base.dev);
+	struct dc *dc = adev->dm.dc;
+
+	/* send extension block to DMCU for parsing */
+	for (i = 0; i < len; i += 8) {
+		bool res;
+		int offset;
+
+		/* send 8 bytes a time */
+		if (!dc_edid_parser_send_cea(dc, i, len, &edid_ext[i], 8))
+			return false;
+
+		if (i+8 == len) {
+			/* EDID block sent completed, expect result */
+			int version, min_rate, max_rate;
+
+			res = dc_edid_parser_recv_amd_vsdb(dc, &version, &min_rate, &max_rate);
+			if (res) {
+				/* amd vsdb found */
+				vsdb_info->freesync_supported = 1;
+				vsdb_info->amd_vsdb_version = version;
+				vsdb_info->min_refresh_rate_hz = min_rate;
+				vsdb_info->max_refresh_rate_hz = max_rate;
+				return true;
+			}
+			/* not amd vsdb */
+			return false;
+		}
+
+		/* check for ack*/
+		res = dc_edid_parser_recv_cea_ack(dc, &offset);
+		if (!res)
+			return false;
+	}
+
+	return false;
+}
+
+static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector,
+		struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info)
+{
+	uint8_t *edid_ext = NULL;
+	int i;
+	bool valid_vsdb_found = false;
+
+	/*----- drm_find_cea_extension() -----*/
+	/* No EDID or EDID extensions */
+	if (edid == NULL || edid->extensions == 0)
+		return false;
+
+	/* Find CEA extension */
+	for (i = 0; i < edid->extensions; i++) {
+		edid_ext = (uint8_t *)edid + EDID_LENGTH * (i + 1);
+		if (edid_ext[0] == CEA_EXT)
+			break;
+	}
+
+	if (i == edid->extensions)
+		return false;
+
+	/*----- cea_db_offsets() -----*/
+	if (edid_ext[0] != CEA_EXT)
+		return false;
+
+	valid_vsdb_found = parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info);
+	return valid_vsdb_found;
+}
+
 void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 					struct edid *edid)
 {
 	int i;
-	bool edid_check_required;
 	struct detailed_timing *timing;
 	struct detailed_non_pixel *data;
 	struct detailed_data_monitor_range *range;
@@ -9642,6 +9722,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 	struct drm_device *dev = connector->dev;
 	struct amdgpu_device *adev = drm_to_adev(dev);
 	bool freesync_capable = false;
+	struct amdgpu_hdmi_vsdb_info vsdb_info = {0};
+	bool hdmi_valid_vsdb_found = false;
 
 	if (!connector->state) {
 		DRM_ERROR("%s - Connector has no state", __func__);
@@ -9660,24 +9742,24 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 
 	dm_con_state = to_dm_connector_state(connector->state);
 
-	edid_check_required = false;
 	if (!amdgpu_dm_connector->dc_sink) {
 		DRM_ERROR("dc_sink NULL, could not add free_sync module.\n");
 		goto update;
 	}
 	if (!adev->dm.freesync_module)
 		goto update;
-	/*
-	 * if edid non zero restrict freesync only for dp and edp
-	 */
-	if (edid) {
+
+
 	if (amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_DISPLAY_PORT
 		|| amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_EDP) {
+		bool edid_check_required = false;
+
+		if (edid) {
 			edid_check_required = is_dp_capable_without_timing_msa(
 						adev->dm.dc,
 						amdgpu_dm_connector);
 		}
-	}
+
 		if (edid_check_required == true && (edid->version > 1 ||
 		   (edid->version == 1 && edid->revision > 1))) {
 			for (i = 0; i < 4; i++) {
@@ -9716,6 +9798,21 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 				freesync_capable = true;
 			}
 		}
+	} else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) {
+		hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info);
+		if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) {
+			timing  = &edid->detailed_timings[i];
+			data    = &timing->data.other_data;
+
+			amdgpu_dm_connector->min_vfreq = vsdb_info.min_refresh_rate_hz;
+			amdgpu_dm_connector->max_vfreq = vsdb_info.max_refresh_rate_hz;
+			if (amdgpu_dm_connector->max_vfreq - amdgpu_dm_connector->min_vfreq > 10)
+				freesync_capable = true;
+
+			connector->display_info.monitor_range.min_vfreq = vsdb_info.min_refresh_rate_hz;
+			connector->display_info.monitor_range.max_vfreq = vsdb_info.max_refresh_rate_hz;
+		}
+	}
 
 update:
 	if (dm_con_state)

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -474,6 +474,14 @@ struct dm_connector_state {
 	uint64_t pbn;
 };
 
+struct amdgpu_hdmi_vsdb_info {
+	unsigned int amd_vsdb_version;		/* VSDB version, should be used to determine which VSIF to send */
+	bool freesync_supported;		/* FreeSync Supported */
+	unsigned int min_refresh_rate_hz;	/* FreeSync Minimum Refresh Rate in Hz */
+	unsigned int max_refresh_rate_hz;	/* FreeSync Maximum Refresh Rate in Hz */
+};
+
+
 #define to_dm_connector_state(x)\
 	container_of((x), struct dm_connector_state, base)