drm/amdgpu: use the AGP aperture for system memory access v2

Start to use the old AGP aperture for system memory access.

v2: Move that to amdgpu_ttm_alloc_gart
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Junwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c

@@ -79,6 +79,29 @@ uint64_t amdgpu_gmc_pd_addr(struct amdgpu_bo *bo)
 	return pd_addr;
 }
 
+/**
+ * amdgpu_gmc_agp_addr - return the address in the AGP address space
+ *
+ * @tbo: TTM BO which needs the address, must be in GTT domain
+ *
+ * Tries to figure out how to access the BO through the AGP aperture. Returns
+ * AMDGPU_BO_INVALID_OFFSET if that is not possible.
+ */
+uint64_t amdgpu_gmc_agp_addr(struct ttm_buffer_object *bo)
+{
+	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->bdev);
+	struct ttm_dma_tt *ttm;
+
+	if (bo->num_pages != 1 || bo->ttm->caching_state == tt_cached)
+		return AMDGPU_BO_INVALID_OFFSET;
+
+	ttm = container_of(bo->ttm, struct ttm_dma_tt, ttm);
+	if (ttm->dma_address[0] + PAGE_SIZE >= adev->gmc.agp_size)
+		return AMDGPU_BO_INVALID_OFFSET;
+
+	return adev->gmc.agp_start + ttm->dma_address[0];
+}
+
 /**
  * amdgpu_gmc_vram_location - try to find VRAM location
  *

drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h

@@ -165,6 +165,7 @@ static inline uint64_t amdgpu_gmc_sign_extend(uint64_t addr)
 void amdgpu_gmc_get_pde_for_bo(struct amdgpu_bo *bo, int level,
 			       uint64_t *addr, uint64_t *flags);
 uint64_t amdgpu_gmc_pd_addr(struct amdgpu_bo *bo);
+uint64_t amdgpu_gmc_agp_addr(struct ttm_buffer_object *bo);
 void amdgpu_gmc_vram_location(struct amdgpu_device *adev, struct amdgpu_gmc *mc,
 			      u64 base);
 void amdgpu_gmc_gart_location(struct amdgpu_device *adev,

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -1081,41 +1081,49 @@ int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo)
 	struct ttm_mem_reg tmp;
 	struct ttm_placement placement;
 	struct ttm_place placements;
-	uint64_t flags;
+	uint64_t addr, flags;
 	int r;
 
 	if (bo->mem.start != AMDGPU_BO_INVALID_OFFSET)
 		return 0;
 
-	/* allocate GART space */
-	tmp = bo->mem;
-	tmp.mm_node = NULL;
-	placement.num_placement = 1;
-	placement.placement = &placements;
-	placement.num_busy_placement = 1;
-	placement.busy_placement = &placements;
-	placements.fpfn = 0;
-	placements.lpfn = adev->gmc.gart_size >> PAGE_SHIFT;
-	placements.flags = (bo->mem.placement & ~TTM_PL_MASK_MEM) |
-		TTM_PL_FLAG_TT;
+	addr = amdgpu_gmc_agp_addr(bo);
+	if (addr != AMDGPU_BO_INVALID_OFFSET) {
+		bo->mem.start = addr >> PAGE_SHIFT;
+	} else {
 
-	r = ttm_bo_mem_space(bo, &placement, &tmp, &ctx);
-	if (unlikely(r))
-		return r;
+		/* allocate GART space */
+		tmp = bo->mem;
+		tmp.mm_node = NULL;
+		placement.num_placement = 1;
+		placement.placement = &placements;
+		placement.num_busy_placement = 1;
+		placement.busy_placement = &placements;
+		placements.fpfn = 0;
+		placements.lpfn = adev->gmc.gart_size >> PAGE_SHIFT;
+		placements.flags = (bo->mem.placement & ~TTM_PL_MASK_MEM) |
+			TTM_PL_FLAG_TT;
+
+		r = ttm_bo_mem_space(bo, &placement, &tmp, &ctx);
+		if (unlikely(r))
+			return r;
 
-	/* compute PTE flags for this buffer object */
-	flags = amdgpu_ttm_tt_pte_flags(adev, bo->ttm, &tmp);
+		/* compute PTE flags for this buffer object */
+		flags = amdgpu_ttm_tt_pte_flags(adev, bo->ttm, &tmp);
 
-	/* Bind pages */
-	gtt->offset = ((u64)tmp.start << PAGE_SHIFT) - adev->gmc.gart_start;
-	r = amdgpu_ttm_gart_bind(adev, bo, flags);
-	if (unlikely(r)) {
-		ttm_bo_mem_put(bo, &tmp);
-		return r;
+		/* Bind pages */
+		gtt->offset = ((u64)tmp.start << PAGE_SHIFT) -
+			adev->gmc.gart_start;
+		r = amdgpu_ttm_gart_bind(adev, bo, flags);
+		if (unlikely(r)) {
+			ttm_bo_mem_put(bo, &tmp);
+			return r;
+		}
+
+		ttm_bo_mem_put(bo, &bo->mem);
+		bo->mem = tmp;
 	}
 
-	ttm_bo_mem_put(bo, &bo->mem);
-	bo->mem = tmp;
 	bo->offset = (bo->mem.start << PAGE_SHIFT) +
 		bo->bdev->man[bo->mem.mem_type].gpu_offset;