>-----Original Message-----
>From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
>Christian König
>Sent: Monday, June 29, 2020 8:22 AM
>To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
>Subject: [PATCH 2/2] drm/ttm: make TT creation purely optional v2
>
>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()
>
>Signed-off-by: Christian König <christian.koenig@xxxxxxx>
>---
> drivers/gpu/drm/ttm/ttm_bo.c | 37 ++++++++-----------------------
> drivers/gpu/drm/ttm/ttm_bo_util.c | 9 ++++++--
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 5 +++++
> drivers/gpu/drm/ttm/ttm_tt.c | 4 +++-
> 4 files changed, 24 insertions(+), 31 deletions(-)
>
>diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
>index 06b8bc0d8f23..c8c25e45751a 100644
>--- 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;
>@@ -1194,13 +1188,8 @@ 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.
>@@ -1217,14 +1206,6 @@ 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 52d2b71f1588..f8414f820350 100644
>--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
>+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
>@@ -580,12 +580,17 @@ 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);
>+ if (!bo->ttm) {
>+ ret = ttm_tt_create(bo, true);
>+ if (ret)
>+ return ret;
>+ }
I think that this chunk can be reduced to:
ret = ttm_tt_create(bo, true);
if (ret)
return ret;
?
With that change (unless I missed something here?):
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Mike
>
>+ 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 0ad30b112982..0586870ab642 100644
>--- 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 2ec448e1d663..e25d4097aa16 100644
>--- 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;
> }
>--
>2.17.1
>
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