Code is expecing to observe the same number of buffers returned from dma_map_sg() function compared to sg_alloc_table_from_pages(). This doesn't hold true universally especially for systems with IOMMU.
IOMMU driver tries to combine buffers into a single DMA address as much as it can. The right thing is to tell the DMA layer how much combining IOMMU can do.
Signed-off-by: Sinan Kaya okaya@codeaurora.org --- drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c | 2 +- drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c | 1 + drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c | 1 + drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 1 + 4 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c index 8e28270..1b031eb 100644 --- a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c @@ -851,7 +851,7 @@ static int gmc_v6_0_sw_init(void *handle) pci_set_consistent_dma_mask(adev->pdev, DMA_BIT_MASK(32)); dev_warn(adev->dev, "amdgpu: No coherent DMA available.\n"); } - + dma_set_max_seg_size(adev->dev, PAGE_SIZE); r = gmc_v6_0_init_microcode(adev); if (r) { dev_err(adev->dev, "Failed to load mc firmware!\n"); diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c index 86e9d682..0a4b2cc1 100644 --- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c @@ -999,6 +999,7 @@ static int gmc_v7_0_sw_init(void *handle) pci_set_consistent_dma_mask(adev->pdev, DMA_BIT_MASK(32)); pr_warn("amdgpu: No coherent DMA available\n"); } + dma_set_max_seg_size(adev->dev, PAGE_SIZE);
r = gmc_v7_0_init_microcode(adev); if (r) { diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c index 9a813d8..b171529 100644 --- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c @@ -1096,6 +1096,7 @@ static int gmc_v8_0_sw_init(void *handle) pci_set_consistent_dma_mask(adev->pdev, DMA_BIT_MASK(32)); pr_warn("amdgpu: No coherent DMA available\n"); } + dma_set_max_seg_size(adev->dev, PAGE_SIZE);
r = gmc_v8_0_init_microcode(adev); if (r) { diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c index 3b7e7af..36e658ab 100644 --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c @@ -855,6 +855,7 @@ static int gmc_v9_0_sw_init(void *handle) pci_set_consistent_dma_mask(adev->pdev, DMA_BIT_MASK(32)); printk(KERN_WARNING "amdgpu: No coherent DMA available.\n"); } + dma_set_max_seg_size(adev->dev, PAGE_SIZE);
r = gmc_v9_0_mc_init(adev); if (r)