On 12/12/25 07:40, Donet Tom wrote: > The SDMA engine has a hardware limitation of 4 MB maximum transfer > size per operation.
That is not correct. This is only true on ancient HW. What problems are you seeing here? > AMDGPU_GTT_MAX_TRANSFER_SIZE was hardcoded to > 512 pages, which worked correctly on systems with 4K pages but fails > on systems with larger page sizes. > > This patch divides the max transfer size / AMDGPU_GPU_PAGES_IN_CPU_PAGE > to match with non-4K page size systems. That is actually a bad idea. The value was meant to match the PMD size. Regards, Christian. > > Signed-off-by: Donet Tom <[email protected]> > Signed-off-by: Ritesh Harjani (IBM) <[email protected]> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h > index 0be2728aa872..9d038feb25b0 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h > @@ -37,7 +37,7 @@ > #define AMDGPU_PL_MMIO_REMAP (TTM_PL_PRIV + 5) > #define __AMDGPU_PL_NUM (TTM_PL_PRIV + 6) > > -#define AMDGPU_GTT_MAX_TRANSFER_SIZE 512 > +#define AMDGPU_GTT_MAX_TRANSFER_SIZE (512 / AMDGPU_GPU_PAGES_IN_CPU_PAGE) > #define AMDGPU_GTT_NUM_TRANSFER_WINDOWS 2 > > extern const struct attribute_group amdgpu_vram_mgr_attr_group;
