The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the
numer of the created entries in the DMA address space. However the
subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be
called with the original number of entries passed to dma_map_sg. The
sg_table->nents in turn holds the result of the dma_map_sg call as stated
in include/linux/scatterlist.h. Adapt the code to obey those rules.

Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.com>
---
 drivers/gpu/drm/panfrost/panfrost_gem.c | 3 ++-
 drivers/gpu/drm/panfrost/panfrost_mmu.c | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c 
b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 17b654e..22fec7c 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -42,7 +42,8 @@ static void panfrost_gem_free_object(struct drm_gem_object 
*obj)
                for (i = 0; i < n_sgt; i++) {
                        if (bo->sgts[i].sgl) {
                                dma_unmap_sg(pfdev->dev, bo->sgts[i].sgl,
-                                            bo->sgts[i].nents, 
DMA_BIDIRECTIONAL);
+                                            bo->sgts[i].orig_nents,
+                                            DMA_BIDIRECTIONAL);
                                sg_free_table(&bo->sgts[i]);
                        }
                }
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c 
b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index ed28aeb..2d9b1f9 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -517,7 +517,9 @@ static int panfrost_mmu_map_fault_addr(struct 
panfrost_device *pfdev, int as,
        if (ret)
                goto err_pages;
 
-       if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) {
+       sgt->nents = dma_map_sg(pfdev->dev, sgt->sgl, sgt->orig_nents,
+                               DMA_BIDIRECTIONAL);
+       if (!sgt->nents) {
                ret = -EINVAL;
                goto err_map;
        }
-- 
1.9.1

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