drm/amd/display: Use freesync when `DRM_EDID_FEATURE_CONTINUOUS_FREQ` found

The monitor shipped with the Framework 16 supports VRR [1], but it's not
being advertised.

This is because the detailed timing block doesn't contain
`EDID_DETAIL_MONITOR_RANGE` which amdgpu looks for to find min and max
frequencies.  This check however is superfluous for this case because
update_display_info() calls drm_get_monitor_range() to get these ranges
already.

So if the `DRM_EDID_FEATURE_CONTINUOUS_FREQ` EDID feature is found then
turn on freesync without extra checks.

v2: squash in fix from Harry

Closes: https://www.reddit.com/r/framework/comments/1b4y2i5/no_variable_refresh_rate_on_the_framework_16_on/
Closes: https://www.reddit.com/r/framework/comments/1b6vzcy/framework_16_variable_refresh_rate/
Closes: https://community.frame.work/t/resolved-no-vrr-freesync-with-amd-version/42338
Link: https://gist.github.com/superm1/e8fbacfa4d0f53150231d3a3e0a13fafSigned-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -11271,18 +11271,24 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 	if (!adev->dm.freesync_module)
 		goto update;
 
-	if (sink->sink_signal == SIGNAL_TYPE_DISPLAY_PORT
-		|| sink->sink_signal == SIGNAL_TYPE_EDP) {
+	if (edid && (sink->sink_signal == SIGNAL_TYPE_DISPLAY_PORT ||
+		     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 (is_dp_capable_without_timing_msa(adev->dm.dc,
+						     amdgpu_dm_connector)) {
+			if (edid->features & DRM_EDID_FEATURE_CONTINUOUS_FREQ) {
+				freesync_capable = true;
+				amdgpu_dm_connector->min_vfreq = connector->display_info.monitor_range.min_vfreq;
+				amdgpu_dm_connector->max_vfreq = connector->display_info.monitor_range.max_vfreq;
+			} else {
+				edid_check_required = edid->version > 1 ||
+						      (edid->version == 1 &&
+						       edid->revision > 1);
+			}
 		}
 
-		if (edid_check_required == true && (edid->version > 1 ||
-		   (edid->version == 1 && edid->revision > 1))) {
+		if (edid_check_required) {
 			for (i = 0; i < 4; i++) {
 
 				timing	= &edid->detailed_timings[i];