From: Thierry Reding <treding@nvidia.com>
Date: Wed, 13 Dec 2017 12:22:48 +0100
Subject: drm/tegra: gem: Map pages via the DMA API
Git-commit: bd43c9f0fa1f664b58eefdc8aab7ac3c8b2026ec
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

When allocating pages, map them with the DMA API in order to invalidate
caches. This is the correct usage of the API and works just as well as
faking up the SG table and using the dma_sync_sg_for_device() function.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/tegra/gem.c |   32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -203,6 +203,8 @@ free:
 static void tegra_bo_free(struct drm_device *drm, struct tegra_bo *bo)
 {
 	if (bo->pages) {
+		dma_unmap_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents,
+			     DMA_BIDIRECTIONAL);
 		drm_gem_put_pages(&bo->gem, bo->pages, true, true);
 		sg_free_table(bo->sgt);
 		kfree(bo->sgt);
@@ -213,8 +215,7 @@ static void tegra_bo_free(struct drm_dev
 
 static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo)
 {
-	struct scatterlist *s;
-	unsigned int i;
+	int err;
 
 	bo->pages = drm_gem_get_pages(&bo->gem);
 	if (IS_ERR(bo->pages))
@@ -223,27 +224,26 @@ static int tegra_bo_get_pages(struct drm
 	bo->num_pages = bo->gem.size >> PAGE_SHIFT;
 
 	bo->sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
-	if (IS_ERR(bo->sgt))
+	if (IS_ERR(bo->sgt)) {
+		err = PTR_ERR(bo->sgt);
 		goto put_pages;
+	}
 
-	/*
-	 * Fake up the SG table so that dma_sync_sg_for_device() can be used
-	 * to flush the pages associated with it.
-	 *
-	 * TODO: Replace this by drm_clflash_sg() once it can be implemented
-	 * without relying on symbols that are not exported.
-	 */
-	for_each_sg(bo->sgt->sgl, s, bo->sgt->nents, i)
-		sg_dma_address(s) = sg_phys(s);
-
-	dma_sync_sg_for_device(drm->dev, bo->sgt->sgl, bo->sgt->nents,
-			       DMA_TO_DEVICE);
+	err = dma_map_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents,
+			 DMA_BIDIRECTIONAL);
+	if (err == 0) {
+		err = -EFAULT;
+		goto free_sgt;
+	}
 
 	return 0;
 
+free_sgt:
+	sg_free_table(bo->sgt);
+	kfree(bo->sgt);
 put_pages:
 	drm_gem_put_pages(&bo->gem, bo->pages, false, false);
-	return PTR_ERR(bo->sgt);
+	return err;
 }
 
 static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo)