drm/vmwgfx: unwind spaghetti code in vmw_dma_select_mode

Just use a simple if/else chain to select the DMA mode.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NThomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: NThomas Hellstrom <thellstrom@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

@@ -566,39 +566,26 @@ static int vmw_dma_select_mode(struct vmw_private *dev_priv)
 		[vmw_dma_map_populate] = "Keeping DMA mappings.",
 		[vmw_dma_map_bind] = "Giving up DMA mappings early."};
 
-	if (intel_iommu_enabled) {
+	if (vmw_force_coherent)
+		dev_priv->map_mode = vmw_dma_alloc_coherent;
+	else if (intel_iommu_enabled)
 		dev_priv->map_mode = vmw_dma_map_populate;
-		goto out_fixup;
-	}
-
-	if (!(vmw_force_iommu || vmw_force_coherent)) {
+	else if (!vmw_force_iommu)
 		dev_priv->map_mode = vmw_dma_phys;
-		DRM_INFO("DMA map mode: %s\n", names[dev_priv->map_mode]);
-		return 0;
-	}
-
-#ifdef CONFIG_SWIOTLB
-	if (swiotlb_nr_tbl())
+	else if (IS_ENABLED(CONFIG_SWIOTLB) && swiotlb_nr_tbl())
 		dev_priv->map_mode = vmw_dma_alloc_coherent;
 	else
-#endif
 		dev_priv->map_mode = vmw_dma_map_populate;
 
-out_fixup:
-	if (dev_priv->map_mode == vmw_dma_map_populate &&
-	    vmw_restrict_iommu)
+	if (dev_priv->map_mode == vmw_dma_map_populate && vmw_restrict_iommu)
 		dev_priv->map_mode = vmw_dma_map_bind;
 
-	if (vmw_force_coherent)
-		dev_priv->map_mode = vmw_dma_alloc_coherent;
-
 	/* No TTM coherent page pool? FIXME: Ask TTM instead! */
         if (!(IS_ENABLED(CONFIG_SWIOTLB) || IS_ENABLED(CONFIG_INTEL_IOMMU)) &&
 	    (dev_priv->map_mode == vmw_dma_alloc_coherent))
 		return -EINVAL;
 
 	DRM_INFO("DMA map mode: %s\n", names[dev_priv->map_mode]);
-
 	return 0;
 }