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/armada/armada_gem.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/armada/armada_gem.c 
b/drivers/gpu/drm/armada/armada_gem.c
index 976685f..749647f 100644
--- a/drivers/gpu/drm/armada/armada_gem.c
+++ b/drivers/gpu/drm/armada/armada_gem.c
@@ -407,8 +407,10 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void 
*data,
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                }
 
-               if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) {
-                       num = sgt->nents;
+               sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents,
+                                       dir);
+               if (sgt->nents == 0) {
+                       num = sgt->orig_nents;
                        goto release;
                }
        } else if (dobj->page) {
@@ -418,7 +420,9 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void 
*data,
 
                sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0);
 
-               if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0)
+               sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents,
+                                       dir);
+               if (sgt->nents == 0)
                        goto free_table;
        } else if (dobj->linear) {
                /* Single contiguous physical region - no struct page */
@@ -449,11 +453,11 @@ static void armada_gem_prime_unmap_dma_buf(struct 
dma_buf_attachment *attach,
        int i;
 
        if (!dobj->linear)
-               dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+               dma_unmap_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir);
 
        if (dobj->obj.filp) {
                struct scatterlist *sg;
-               for_each_sg(sgt->sgl, sg, sgt->nents, i)
+               for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
                        put_page(sg_page(sg));
        }
 
-- 
1.9.1

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