--- ./amd/amdgpu/gmc_v8_0.c.orig	2019-07-23 18:08:14.902391363 +0000
+++ ./amd/amdgpu/gmc_v8_0.c	2019-07-23 18:10:42.879052582 +0000
@@ -1139,7 +1139,11 @@
 		pci_set_consistent_dma_mask(adev->pdev, DMA_BIT_MASK(32));
 		pr_warn("amdgpu: No coherent DMA available\n");
 	}
+#if DRM_VERSION_CODE >= DRM_VERSION(5, 2, 0)
+	adev->need_swiotlb = drm_need_swiotlb(dma_bits);
+#else
 	adev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
+#endif
 
 	r = gmc_v8_0_init_microcode(adev);
 	if (r) {