drm/radeon: halt engines before disabling MC (si)

It's better to halt the engines before we disable the MC.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/si.c

@@ -2220,11 +2220,6 @@ static void si_gpu_soft_reset(struct radeon_device *rdev, u32 reset_mask)
 	dev_info(rdev->dev, "  VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x%08X\n",
 		 RREG32(VM_CONTEXT1_PROTECTION_FAULT_STATUS));
 
-	evergreen_mc_stop(rdev, &save);
-	if (evergreen_mc_wait_for_idle(rdev)) {
-		dev_warn(rdev->dev, "Wait for MC idle timedout !\n");
-	}
-
 	/* Disable CP parsing/prefetching */
 	WREG32(CP_ME_CNTL, CP_ME_HALT | CP_PFP_HALT | CP_CE_HALT);
 
@@ -2241,6 +2236,13 @@ static void si_gpu_soft_reset(struct radeon_device *rdev, u32 reset_mask)
 		WREG32(DMA_RB_CNTL + DMA1_REGISTER_OFFSET, tmp);
 	}
 
+	udelay(50);
+
+	evergreen_mc_stop(rdev, &save);
+	if (evergreen_mc_wait_for_idle(rdev)) {
+		dev_warn(rdev->dev, "Wait for MC idle timedout !\n");
+	}
+
 	if (reset_mask & (RADEON_RESET_GFX | RADEON_RESET_COMPUTE | RADEON_RESET_CP)) {
 		grbm_soft_reset = SOFT_RESET_CB |
 			SOFT_RESET_DB |