On 4/17/2018 11:58 AM, Robin Murphy wrote: > 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, > Tested-by: Sinan Kaya <okaya at codeaurora.org> using QDF2400 and XFX Vega64 GPU for the first two patches. ./builddir/tests/amdgpu/amdgpu_test -s 1 Suite: Basic Tests Test: Userptr Test ...passed Userptr Test fails without this patch. -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
