From ebdf565169af006ee3be8c40eecbfc77d28a3b84 Mon Sep 17 00:00:00 2001 From: Dave Airlie Date: Thu, 29 Oct 2020 13:58:52 +1000 Subject: drm/ttm: add multihop infrastrucutre (v3) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: hristian König Signed-off-by: Dave Airlie Link: https://patchwork.freedesktop.org/patch/msgid/20201109005432.861936-2-airlied@gmail.com --- drivers/gpu/drm/ttm/ttm_bo.c | 74 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 65 insertions(+), 9 deletions(-) (limited to 'drivers/gpu/drm/ttm/ttm_bo.c') 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; + } } /** -- cgit v1.2.3