Jerome Glisse wrote:
> Hi Thomas,
>
> I am not sure of the correct solution for moving a bo from
> VRAM to SYSTEM when you need to go through TT, here are
> solution i thought of and why they are wrong:
>
> (in driver callback move i get bo & newmem with bo being
> in vram and newmem being SYSTEM)
>
> 1) ttm_bo_move_buffer(bo, TT, ...);
> 2) move_null(bo, new_mem);
>
> Problem:
> 1) Will find space in tt and create a new node it will
> then call handle move mem which will allocate pages
> & bind to tt and callback into the driver move which
> will emit blit to do the actual copy
> It will also create a ghost object for holding the
> vram node until blit is done.
> 2) According to openchrome implementation i should bug
> if old_mem->mm_node != NULL which is at this point
> the case as mm_node is now a node of tt allocated
> memory and i can't free this node as i need to
> wait for the blit to finish
>
>
> 1) ttm_bo_move_buffer(bo, TT, ...);
> 2) ttm_bo_move_accel_cleanup(bo, ?syncobj?, new_mem);
>
> I think it's the right solution so there is 2 ghost
> object created but i am wondering if i have right
> to do it.
> 1) create ghost holding vram node
> 2) will create another ghost holding the tt node
> but the sync obj i provide should be the same
> as for the ghost of 1. I could know the syncobj
> and use it but does it sounds like what i want
> to do ?
>
> Cheers,
> Jerome
>
>
Jerome,
Below is what Moorestown/Poulsbo does for the same thing.
However, the Moorestown / Poulsbo MMU can deal with cached page table
entries,
so depending on whether or not the Radeon can do that, you might want to
adjust
tmp_mem.caching flags.
The ttm_bo_handle_move_mem function may also need some patching to avoid
calling
ttm_tt_set_placement_caching for the new ttm, and instead let the driver
move code do that.
static int psb_move_blit(struct ttm_buffer_object *bo,
bool evict, bool no_wait,
struct ttm_mem_reg *new_mem)
{
struct drm_psb_private *dev_priv =
container_of(bo->bdev, struct drm_psb_private, bdev);
struct drm_device *dev = dev_priv->dev;
struct ttm_mem_reg *old_mem = &bo->mem;
struct ttm_fence_object *fence;
int dir = 0;
int ret;
if ((old_mem->mem_type == new_mem->mem_type) &&
(new_mem->mm_node->start <
old_mem->mm_node->start + old_mem->mm_node->size)) {
dir = 1;
}
psb_emit_2d_copy_blit(dev,
old_mem->mm_node->start << PAGE_SHIFT,
new_mem->mm_node->start << PAGE_SHIFT,
new_mem->num_pages, dir);
ret = ttm_fence_object_create(&dev_priv->fdev, 0,
_PSB_FENCE_TYPE_EXE,
TTM_FENCE_FLAG_EMIT,
&fence);
if (unlikely(ret != 0)) {
psb_idle_2d(dev);
if (fence)
ttm_fence_object_unref(&fence);
}
ret = ttm_bo_move_accel_cleanup(bo, (void *) fence,
(void *) (unsigned long)
_PSB_FENCE_TYPE_EXE,
evict, no_wait, new_mem);
if (fence)
ttm_fence_object_unref(&fence);
return ret;
}
/*
* Flip destination ttm into GATT,
* then blit and subsequently move out again.
*/
static int psb_move_flip(struct ttm_buffer_object *bo,
bool evict, bool interruptible, bool no_wait,
struct ttm_mem_reg *new_mem)
{
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_mem_reg tmp_mem;
int ret;
tmp_mem = *new_mem;
tmp_mem.mm_node = NULL;
tmp_mem.proposed_flags = TTM_PL_FLAG_TT;
ret = ttm_bo_mem_space(bo, &tmp_mem, interruptible, no_wait);
if (ret)
return ret;
ret = ttm_tt_bind(bo->ttm, &tmp_mem);
if (ret)
goto out_cleanup;
ret = psb_move_blit(bo, true, no_wait, &tmp_mem);
if (ret)
goto out_cleanup;
ret = ttm_bo_move_ttm(bo, evict, no_wait, new_mem);
out_cleanup:
if (tmp_mem.mm_node) {
spin_lock(&bdev->lru_lock);
drm_mm_put_block(tmp_mem.mm_node);
tmp_mem.mm_node = NULL;
spin_unlock(&bdev->lru_lock);
}
return ret;
}
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