drm/amd/display: Fix VRR cannot enable

[Why]
Sometimes the VRR cannot enable after login to the desktop.

User space may call the DRM_IOCTL_MODE_GETCONNECTOR right after
the DRM_IOCTL_MODE_RMFB.

After calling DRM_IOCTL_MODE_RMFB to remove all the frame buffer
and it will cause the driver to disable the crtc and disable the
link while calling the link_set_dpms_off().

It will cause the dpcd read failed in amdgpu_dm_update_freesync_caps()
while try to get the DP_MSA_TIMING_PAR_IGNORED capability and think
the sink side does not support VRR.

[How]
Use the dpcd_caps.allow_invalid_MSA_timing_param flag instead of
reading from dpcd directly.

dpcd_caps.allow_invalid_MSA_timing_param flag is updated during HPD.
It is safe to replace the original method.
Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@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

@@ -11721,25 +11721,6 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 	return ret;
 }
 
-static bool is_dp_capable_without_timing_msa(struct dc *dc,
-					     struct amdgpu_dm_connector *amdgpu_dm_connector)
-{
-	u8 dpcd_data;
-	bool capable = false;
-
-	if (amdgpu_dm_connector->dc_link &&
-		dm_helpers_dp_read_dpcd(
-				NULL,
-				amdgpu_dm_connector->dc_link,
-				DP_DOWN_STREAM_PORT_COUNT,
-				&dpcd_data,
-				sizeof(dpcd_data))) {
-		capable = (dpcd_data & DP_MSA_TIMING_PAR_IGNORED) ? true:false;
-	}
-
-	return capable;
-}
-
 static bool dm_edid_parser_send_cea(struct amdgpu_display_manager *dm,
 		unsigned int offset,
 		unsigned int total_length,
@@ -12042,8 +12023,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector,
 		     sink->sink_signal == SIGNAL_TYPE_EDP)) {
 		bool edid_check_required = false;
 
-		if (is_dp_capable_without_timing_msa(adev->dm.dc,
-						     amdgpu_dm_connector)) {
+		if (amdgpu_dm_connector->dc_link &&
+		    amdgpu_dm_connector->dc_link->dpcd_caps.allow_invalid_MSA_timing_param) {
 			if (edid->features & DRM_EDID_FEATURE_CONTINUOUS_FREQ) {
 				amdgpu_dm_connector->min_vfreq = connector->display_info.monitor_range.min_vfreq;
 				amdgpu_dm_connector->max_vfreq = connector->display_info.monitor_range.max_vfreq;