drm/ttm: make TT creation purely optional v3

We only need the page array when the BO is about to be accessed.

So not only populate, but also create it on demand.

v2: move NULL check into ttm_tt_create()
v3: fix the occurrence in ttm_bo_kmap_ttm as well

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Link: https://patchwork.freedesktop.org/patch/373182/

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 2da8dbd2553b2a7484554d1719e50f7eeaaee025..0c13fe96c7e33919b49b56f623eca9a89d657d99 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -292,12 +292,11 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
         */
 
        if (!(new_man->flags & TTM_MEMTYPE_FLAG_FIXED)) {
-               if (bo->ttm == NULL) {
-                       bool zero = !(old_man->flags & TTM_MEMTYPE_FLAG_FIXED);
-                       ret = ttm_tt_create(bo, zero);
-                       if (ret)
-                               goto out_err;
-               }
+               bool zero = !(old_man->flags & TTM_MEMTYPE_FLAG_FIXED);
+
+               ret = ttm_tt_create(bo, zero);
+               if (ret)
+                       goto out_err;
 
                ret = ttm_tt_set_placement_caching(bo->ttm, mem->placement);
                if (ret)
@@ -660,13 +659,8 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
        placement.num_busy_placement = 0;
        bdev->driver->evict_flags(bo, &placement);
 
-       if (!placement.num_placement && !placement.num_busy_placement) {
-               ret = ttm_bo_pipeline_gutting(bo);
-               if (ret)
-                       return ret;
-
-               return ttm_tt_create(bo, false);
-       }
+       if (!placement.num_placement && !placement.num_busy_placement)
+               return ttm_bo_pipeline_gutting(bo);
 
        evict_mem = bo->mem;
        evict_mem.mm_node = NULL;
@@ -1195,13 +1189,8 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
        /*
         * Remove the backing store if no placement is given.
         */
-       if (!placement->num_placement && !placement->num_busy_placement) {
-               ret = ttm_bo_pipeline_gutting(bo);
-               if (ret)
-                       return ret;
-
-               return ttm_tt_create(bo, false);
-       }
+       if (!placement->num_placement && !placement->num_busy_placement)
+               return ttm_bo_pipeline_gutting(bo);
 
        /*
         * Check whether we need to move buffer.
@@ -1218,14 +1207,6 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
                ttm_flag_masked(&bo->mem.placement, new_flags,
                                ~TTM_PL_MASK_MEMTYPE);
        }
-       /*
-        * We might need to add a TTM.
-        */
-       if (bo->mem.mem_type == TTM_PL_SYSTEM && bo->ttm == NULL) {
-               ret = ttm_tt_create(bo, true);
-               if (ret)
-                       return ret;
-       }
        return 0;
 }
 EXPORT_SYMBOL(ttm_bo_validate);

diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index f09b096ba4fda815a30c82d45a280ac2877d89d1..5e0f3a9caedc4ad0374666daf183755050349b7d 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -532,12 +532,15 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
                .interruptible = false,
                .no_wait_gpu = false
        };
-       struct ttm_tt *ttm = bo->ttm;
+       struct ttm_tt *ttm;
        pgprot_t prot;
        int ret;
 
-       BUG_ON(!ttm);
+       ret = ttm_tt_create(bo, true);
+       if (ret)
+               return ret;
 
+       ttm = bo->ttm;
        ret = ttm_tt_populate(ttm, &ctx);
        if (ret)
                return ret;

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index a43aa7275f126a6e9b55aa0f2c8b845244208669..82b893d4249f5cce851c6f3aa9c26b55d82b653b 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -349,6 +349,11 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 
                };
 
+               if (ttm_tt_create(bo, true)) {
+                       ret = VM_FAULT_OOM;
+                       goto out_io_unlock;
+               }
+
                ttm = bo->ttm;
                if (ttm_tt_populate(bo->ttm, &ctx)) {
                        ret = VM_FAULT_OOM;

diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 2ec448e1d663dc452084b043584dec359ed4ea29..e25d4097aa1680339868f891f309dedfd9a8a22c 100644 (file)
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -50,6 +50,9 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc)
 
        dma_resv_assert_held(bo->base.resv);
 
+       if (bo->ttm)
+               return 0;
+
        if (bdev->need_dma32)
                page_flags |= TTM_PAGE_FLAG_DMA32;
 
@@ -67,7 +70,6 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc)
                page_flags |= TTM_PAGE_FLAG_SG;
                break;
        default:
-               bo->ttm = NULL;
                pr_err("Illegal buffer object type\n");
                return -EINVAL;
        }