The amdgpu driver doesn't appear to directly use the scatterlist mapped by amdgpu_ttm_tt_pin_userptr(), it merely hands it off to drm_prime_sg_to_page_addr_arrays() to generate the dma_address array which it actually cares about. Now that the latter can cope with dma_map_sg() coalescing dma-contiguous segments such that it returns 0 < count < nents, we can relax the current count == nents check to only consider genuine failure as other drivers do. This avoids a false negative on arm64 systems with an IOMMU. Reported-by: Sinan Kaya <okaya at codeaurora.org> Signed-off-by: Robin Murphy <robin.murphy at arm.com> --- v2: Expand commit message to clarify drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index 205da3ff9cd0..f81e96a4242f 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -813,7 +813,7 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm) r = -ENOMEM; nents = dma_map_sg(adev->dev, ttm->sg->sgl, ttm->sg->nents, direction); - if (nents != ttm->sg->nents) + if (nents == 0) goto release_sg; drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages, -- 2.16.1.dirty
