1 files changed, 32 insertions, 4 deletions

diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
index da32086cbeaf..c888bed4036f 100644
--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -219,19 +219,47 @@ 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)
 {
+        struct scatterlist *s;
+        struct sg_table *sgt;
+        unsigned int i;
+
         bo->pages = drm_gem_get_pages(&bo->gem);
         if (IS_ERR(bo->pages))
                 return PTR_ERR(bo->pages);
 
         bo->num_pages = size >> PAGE_SHIFT;
 
-        bo->sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
-        if (IS_ERR(bo->sgt)) {
-                drm_gem_put_pages(&bo->gem, bo->pages, false, false);
-                return PTR_ERR(bo->sgt);
+        sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
+        if (IS_ERR(sgt))
+                goto put_pages;
+
+        /*
+         * Fake up the SG table so that dma_map_sg() can be used to flush the
+         * pages associated with it. Note that this relies on the fact that
+         * the DMA API doesn't hook into IOMMU on Tegra, therefore mapping is
+         * only cache maintenance.
+         *
+         * TODO: Replace this by drm_clflash_sg() once it can be implemented
+         * without relying on symbols that are not exported.
+         */
+        for_each_sg(sgt->sgl, s, sgt->nents, i)
+                sg_dma_address(s) = sg_phys(s);
+
+        if (dma_map_sg(drm->dev, sgt->sgl, sgt->nents, DMA_TO_DEVICE) == 0) {
+                sgt = ERR_PTR(-ENOMEM);
+                goto release_sgt;
         }
 
+        bo->sgt = sgt;
+
         return 0;
+
+release_sgt:
+        sg_free_table(sgt);
+        kfree(sgt);
+put_pages:
+        drm_gem_put_pages(&bo->gem, bo->pages, false, false);
+        return PTR_ERR(sgt);
 }
 
 static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo,