drm/tegra: gem: Use the proper size for GEM objects

If the requested buffer size wasn't a multiple of the page size, the
IOMMU code would round down the size to the next multiple of the page
size, thereby causing translation errors. To fix this we no longer pass
around the requested size but reuse the computed size of the GEM object.
This is already rounded to the next page boundary, so mapping that size
works out fine.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/gem.c

@@ -216,8 +216,7 @@ static void tegra_bo_free(struct drm_device *drm, struct tegra_bo *bo)
 	}
 }
 
-static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo,
-			      size_t size)
+static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo)
 {
 	struct scatterlist *s;
 	struct sg_table *sgt;
@@ -227,7 +226,7 @@ static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo,
 	if (IS_ERR(bo->pages))
 		return PTR_ERR(bo->pages);
 
-	bo->num_pages = size >> PAGE_SHIFT;
+	bo->num_pages = bo->gem.size >> PAGE_SHIFT;
 
 	sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
 	if (IS_ERR(sgt))
@@ -262,14 +261,13 @@ static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo,
 	return PTR_ERR(sgt);
 }
 
-static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo,
-			  size_t size)
+static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo)
 {
 	struct tegra_drm *tegra = drm->dev_private;
 	int err;
 
 	if (tegra->domain) {
-		err = tegra_bo_get_pages(drm, bo, size);
+		err = tegra_bo_get_pages(drm, bo);
 		if (err < 0)
 			return err;
 
@@ -279,6 +277,8 @@ static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo,
 			return err;
 		}
 	} else {
+		size_t size = bo->gem.size;
+
 		bo->vaddr = dma_alloc_writecombine(drm->dev, size, &bo->paddr,
 						   GFP_KERNEL | __GFP_NOWARN);
 		if (!bo->vaddr) {
@@ -302,7 +302,7 @@ struct tegra_bo *tegra_bo_create(struct drm_device *drm, size_t size,
 	if (IS_ERR(bo))
 		return bo;
 
-	err = tegra_bo_alloc(drm, bo, size);
+	err = tegra_bo_alloc(drm, bo);
 	if (err < 0)
 		goto release;