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authorDave Airlie <airlied@redhat.com>2020-10-29 13:58:52 +1000
committerDave Airlie <airlied@redhat.com>2020-11-11 11:11:03 +1000
commitebdf565169af006ee3be8c40eecbfc77d28a3b84 (patch)
treeccc29cae7148ec2940d137a6492852dc1d6f1ff9 /drivers/gpu/drm/ttm
parent2dcab875e7637f1d3f9b978566e61ed1cbbba054 (diff)
drm/ttm: add multihop infrastrucutre (v3)
Currently drivers get called to move a buffer, but if they have to move it temporarily through another space (SYSTEM->VRAM via TT) then they can end up with a lot of ttm->driver->ttm call stacks, if the temprorary space moves requires eviction. Instead of letting the driver do all the placement/space for the temporary, allow it to report back (-EMULTIHOP) and a placement (hop) to the move code, which will then do the temporary move, and the correct placement move afterwards. This removes a lot of code from drivers, at the expense of adding some midlayering. I've some further ideas on how to turn it inside out, but I think this is a good solution to the call stack problems. v2: separate out the driver patches, add WARN for getting MULTHOP in paths we shouldn't (Daniel) v3: use memset (Christian) Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: hristian König <christian.koenig@amd.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20201109005432.861936-2-airlied@gmail.com
Diffstat (limited to 'drivers/gpu/drm/ttm')
-rw-r--r--drivers/gpu/drm/ttm/ttm_bo.c74
1 files changed, 65 insertions, 9 deletions
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index e2a124b3affb..e6bcbfe530ec 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -231,7 +231,8 @@ EXPORT_SYMBOL(ttm_bo_bulk_move_lru_tail);
static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
struct ttm_resource *mem, bool evict,
- struct ttm_operation_ctx *ctx)
+ struct ttm_operation_ctx *ctx,
+ struct ttm_place *hop)
{
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_resource_manager *old_man = ttm_manager_type(bdev, bo->mem.mem_type);
@@ -259,9 +260,12 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
}
}
- ret = bdev->driver->move(bo, evict, ctx, mem);
- if (ret)
+ ret = bdev->driver->move(bo, evict, ctx, mem, hop);
+ if (ret) {
+ if (ret == -EMULTIHOP)
+ return ret;
goto out_err;
+ }
ctx->bytes_moved += bo->num_pages << PAGE_SHIFT;
return 0;
@@ -566,8 +570,11 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_resource evict_mem;
struct ttm_placement placement;
+ struct ttm_place hop;
int ret = 0;
+ memset(&hop, 0, sizeof(hop));
+
dma_resv_assert_held(bo->base.resv);
placement.num_placement = 0;
@@ -596,8 +603,9 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
goto out;
}
- ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, ctx);
+ ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, ctx, &hop);
if (unlikely(ret)) {
+ WARN(ret == -EMULTIHOP, "Unexpected multihop in eviction - likely driver bug\n");
if (ret != -ERESTARTSYS)
pr_err("Buffer eviction failed\n");
ttm_resource_free(bo, &evict_mem);
@@ -936,15 +944,45 @@ error:
}
EXPORT_SYMBOL(ttm_bo_mem_space);
+static int ttm_bo_bounce_temp_buffer(struct ttm_buffer_object *bo,
+ struct ttm_resource *mem,
+ struct ttm_operation_ctx *ctx,
+ struct ttm_place *hop)
+{
+ struct ttm_placement hop_placement;
+ int ret;
+ struct ttm_resource hop_mem = *mem;
+
+ hop_mem.mm_node = NULL;
+ hop_mem.mem_type = TTM_PL_SYSTEM;
+ hop_mem.placement = 0;
+
+ hop_placement.num_placement = hop_placement.num_busy_placement = 1;
+ hop_placement.placement = hop_placement.busy_placement = hop;
+
+ /* find space in the bounce domain */
+ ret = ttm_bo_mem_space(bo, &hop_placement, &hop_mem, ctx);
+ if (ret)
+ return ret;
+ /* move to the bounce domain */
+ ret = ttm_bo_handle_move_mem(bo, &hop_mem, false, ctx, NULL);
+ if (ret)
+ return ret;
+ return 0;
+}
+
static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
struct ttm_placement *placement,
struct ttm_operation_ctx *ctx)
{
int ret = 0;
+ struct ttm_place hop;
struct ttm_resource mem;
dma_resv_assert_held(bo->base.resv);
+ memset(&hop, 0, sizeof(hop));
+
mem.num_pages = bo->num_pages;
mem.size = mem.num_pages << PAGE_SHIFT;
mem.page_alignment = bo->mem.page_alignment;
@@ -954,12 +992,25 @@ static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
/*
* Determine where to move the buffer.
+ *
+ * If driver determines move is going to need
+ * an extra step then it will return -EMULTIHOP
+ * and the buffer will be moved to the temporary
+ * stop and the driver will be called to make
+ * the second hop.
*/
+bounce:
ret = ttm_bo_mem_space(bo, placement, &mem, ctx);
if (ret)
- goto out_unlock;
- ret = ttm_bo_handle_move_mem(bo, &mem, false, ctx);
-out_unlock:
+ return ret;
+ ret = ttm_bo_handle_move_mem(bo, &mem, false, ctx, &hop);
+ if (ret == -EMULTIHOP) {
+ ret = ttm_bo_bounce_temp_buffer(bo, &mem, ctx, &hop);
+ if (ret)
+ return ret;
+ /* try and move to final place now. */
+ goto bounce;
+ }
if (ret)
ttm_resource_free(bo, &mem);
return ret;
@@ -1432,15 +1483,20 @@ int ttm_bo_swapout(struct ttm_operation_ctx *ctx)
if (bo->mem.mem_type != TTM_PL_SYSTEM) {
struct ttm_operation_ctx ctx = { false, false };
struct ttm_resource evict_mem;
+ struct ttm_place hop;
+
+ memset(&hop, 0, sizeof(hop));
evict_mem = bo->mem;
evict_mem.mm_node = NULL;
evict_mem.placement = 0;
evict_mem.mem_type = TTM_PL_SYSTEM;
- ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, &ctx);
- if (unlikely(ret != 0))
+ ret = ttm_bo_handle_move_mem(bo, &evict_mem, true, &ctx, &hop);
+ if (unlikely(ret != 0)) {
+ WARN(ret == -EMULTIHOP, "Unexpected multihop in swaput - likely driver bug.\n");
goto out;
+ }
}
/**