nouveau: use ttm populate mapping functions. (v2)

Instead of rolling driver copies of them.

v2: cleanup return handling (Ben)
Reviewed-by: NBen Skeggs <bskeggs@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200804025632.3868079-4-airlied@gmail.com

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -1526,8 +1526,6 @@ nouveau_ttm_tt_populate(struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
 	struct ttm_dma_tt *ttm_dma = (void *)ttm;
 	struct nouveau_drm *drm;
 	struct device *dev;
-	unsigned i;
-	int r;
 	bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG);
 
 	if (ttm->state != tt_unpopulated)
@@ -1555,31 +1553,7 @@ nouveau_ttm_tt_populate(struct ttm_tt *ttm, struct ttm_operation_ctx *ctx)
 		return ttm_dma_populate((void *)ttm, dev, ctx);
 	}
 #endif
-
-	r = ttm_pool_populate(ttm, ctx);
-	if (r) {
-		return r;
-	}
-
-	for (i = 0; i < ttm->num_pages; i++) {
-		dma_addr_t addr;
-
-		addr = dma_map_page(dev, ttm->pages[i], 0, PAGE_SIZE,
-				    DMA_BIDIRECTIONAL);
-
-		if (dma_mapping_error(dev, addr)) {
-			while (i--) {
-				dma_unmap_page(dev, ttm_dma->dma_address[i],
-					       PAGE_SIZE, DMA_BIDIRECTIONAL);
-				ttm_dma->dma_address[i] = 0;
-			}
-			ttm_pool_unpopulate(ttm);
-			return -EFAULT;
-		}
-
-		ttm_dma->dma_address[i] = addr;
-	}
-	return 0;
+	return ttm_populate_and_map_pages(dev, ttm_dma, ctx);
 }
 
 static void
@@ -1588,7 +1562,6 @@ nouveau_ttm_tt_unpopulate(struct ttm_tt *ttm)
 	struct ttm_dma_tt *ttm_dma = (void *)ttm;
 	struct nouveau_drm *drm;
 	struct device *dev;
-	unsigned i;
 	bool slave = !!(ttm->page_flags & TTM_PAGE_FLAG_SG);
 
 	if (slave)
@@ -1611,14 +1584,7 @@ nouveau_ttm_tt_unpopulate(struct ttm_tt *ttm)
 	}
 #endif
 
-	for (i = 0; i < ttm->num_pages; i++) {
-		if (ttm_dma->dma_address[i]) {
-			dma_unmap_page(dev, ttm_dma->dma_address[i], PAGE_SIZE,
-				       DMA_BIDIRECTIONAL);
-		}
-	}
-
-	ttm_pool_unpopulate(ttm);
+	ttm_unmap_and_unpopulate_pages(dev, ttm_dma);
 }
 
 void