ttm: add prime sharing support to TTM (v2)

This adds the ability for ttm common code to take an SG table
and use it as the backing for a slave TTM object.

The drivers can then populate their GTT tables using the SG object.

v2: make sure to setup VM for sg bos as well.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 1f5c67c579cf..36792bd4da77 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -343,6 +343,16 @@ static int ttm_bo_add_ttm(struct ttm_buffer_object *bo, bool zero_alloc)
                 if (unlikely(bo->ttm == NULL))
                         ret = -ENOMEM;
                 break;
+        case ttm_bo_type_sg:
+                bo->ttm = bdev->driver->ttm_tt_create(bdev, bo->num_pages << PAGE_SHIFT,
+                                                      page_flags | TTM_PAGE_FLAG_SG,
+                                                      glob->dummy_read_page);
+                if (unlikely(bo->ttm == NULL)) {
+                        ret = -ENOMEM;
+                        break;
+                }
+                bo->ttm->sg = bo->sg;
+                break;
         default:
                 pr_err("Illegal buffer object type\n");
                 ret = -EINVAL;
@@ -1169,6 +1179,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
                 bool interruptible,
                 struct file *persistent_swap_storage,
                 size_t acc_size,
+                struct sg_table *sg,
                 void (*destroy) (struct ttm_buffer_object *))
 {
         int ret = 0;
@@ -1223,6 +1234,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
         bo->seq_valid = false;
         bo->persistent_swap_storage = persistent_swap_storage;
         bo->acc_size = acc_size;
+        bo->sg = sg;
         atomic_inc(&bo->glob->bo_count);
 
         ret = ttm_bo_check_placement(bo, placement);
@@ -1233,7 +1245,8 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
          * For ttm_bo_type_device buffers, allocate
          * address space from the device.
          */
-        if (bo->type == ttm_bo_type_device) {
+        if (bo->type == ttm_bo_type_device ||
+            bo->type == ttm_bo_type_sg) {
                 ret = ttm_bo_setup_vm(bo);
                 if (ret)
                         goto out_err;
@@ -1312,7 +1325,7 @@ int ttm_bo_create(struct ttm_bo_device *bdev,
 
         ret = ttm_bo_init(bdev, bo, size, type, placement, page_alignment,
                                 buffer_start, interruptible,
-                                persistent_swap_storage, acc_size, NULL);
+                          persistent_swap_storage, acc_size, NULL, NULL);
         if (likely(ret == 0))
                 *p_bo = bo;