[RFC 8/8] drm/xe/pt: Add an additional check for dmabuf BOs while doing bind

[Vivek Kasireddy <vivek.kasireddy@intel.com>]

If a BO's is_devmem_external flag is set, it means that it is an
imported dmabuf BO that has a backing store in VRAM. Therefore, in
this case, need to iterate over its dma_addr array.

v2:
- Use a cursor to iterate over the entries in the dma_addr array
  instead of relying on SG iterator (Matt)

v3:
- Since XE_PPGTT_PTE_DM is added to the PTE flags in all cases,
  remove the bo->is_devmem_external check added in v2

Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 drivers/gpu/drm/xe/xe_pt.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
index a1c88f9a6c76..5cc3775a3a12 100644
--- a/drivers/gpu/drm/xe/xe_pt.c
+++ b/drivers/gpu/drm/xe/xe_pt.c
@@ -759,6 +759,10 @@ xe_pt_stage_bind(struct xe_tile *tile, struct xe_vma *vma,
 
 	xe_walk.default_vram_pte |= XE_PPGTT_PTE_DM;
 	xe_walk.dma_offset = bo ? vram_region_gpu_offset(bo->ttm.resource) : 0;
+
+	if (bo && bo->is_devmem_external)
+		xe_walk.dma_offset = 0;
+
 	if (!range)
 		xe_bo_assert_held(bo);
 
@@ -769,6 +773,10 @@ xe_pt_stage_bind(struct xe_tile *tile, struct xe_vma *vma,
 		else if (xe_bo_is_vram(bo) || xe_bo_is_stolen(bo))
 			xe_res_first(bo->ttm.resource, xe_vma_bo_offset(vma),
 				     xe_vma_size(vma), &curs);
+		else if (bo && bo->is_devmem_external)
+			xe_res_first_dma(bo->dma_data.dma_addr,
+					 xe_vma_bo_offset(vma),
+					 xe_vma_size(vma), &curs);
 		else
 			xe_res_first_sg(xe_bo_sg(bo), xe_vma_bo_offset(vma),
 					xe_vma_size(vma), &curs);
-- 
2.50.1