drm/amd/pm: fixes a random hang in S4 for SMU v13.0.4/11

While doing multiple S4 stress tests, GC/RLC/PMFW get into
an invalid state resulting into hard hangs.

Adding a GFX reset as workaround just before sending the
MP1_UNLOAD message avoids this failure.
Signed-off-by: Tim Huang <Tim.Huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0_4_ppt.c

@@ -226,8 +226,18 @@ static int smu_v13_0_4_system_features_control(struct smu_context *smu, bool en)
 	struct amdgpu_device *adev = smu->adev;
 	int ret = 0;
 
-	if (!en && !adev->in_s0ix)
+	if (!en && !adev->in_s0ix) {
+		/* Adds a GFX reset as workaround just before sending the
+		 * MP1_UNLOAD message to prevent GC/RLC/PMFW from entering
+		 * an invalid state.
+		 */
+		ret = smu_cmn_send_smc_msg_with_param(smu, SMU_MSG_GfxDeviceDriverReset,
+						      SMU_RESET_MODE_2, NULL);
+		if (ret)
+			return ret;
+
 		ret = smu_cmn_send_smc_msg(smu, SMU_MSG_PrepareMp1ForUnload, NULL);
+	}
 
 	return ret;
 }