Hi guys,
at least on amdgpu and radeon the page array allocated by
ttm_dma_tt_init is completely unused in the case of DMA-buf sharing. So
I'm trying to get rid of that by only allocating the DMA address array.
Now the only other user of DMA-buf together with ttm_dma_tt_init is
Nouveau. So my question is are you guys using the page array anywhere in
your kernel driver in case of a DMA-buf sharing?
If no then I could just make this the default behavior for all drivers
and save quite a bit of memory for everybody.
Thanks,
Christian.
Am 27.02.2018 um 12:49 schrieb Christian König:
> This allows drivers to only allocate dma addresses, but not a page
> array.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
> drivers/gpu/drm/ttm/ttm_tt.c | 54 ++++++++++++++++++++++++++++++++++++--------
> include/drm/ttm/ttm_tt.h | 2 ++
> 2 files changed, 47 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
> index 8e0b525cda00..971133106ec2 100644
> --- a/drivers/gpu/drm/ttm/ttm_tt.c
> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
> @@ -108,6 +108,16 @@ static int ttm_dma_tt_alloc_page_directory(struct ttm_dma_tt *ttm)
> return 0;
> }
>
> +static int ttm_sg_tt_alloc_page_directory(struct ttm_dma_tt *ttm)
> +{
> + ttm->dma_address = kvmalloc_array(ttm->ttm.num_pages,
> + sizeof(*ttm->dma_address),
> + GFP_KERNEL | __GFP_ZERO);
> + if (!ttm->dma_address)
> + return -ENOMEM;
> + return 0;
> +}
> +
> #ifdef CONFIG_X86
> static inline int ttm_tt_set_page_caching(struct page *p,
> enum ttm_caching_state c_old,
> @@ -227,8 +237,8 @@ void ttm_tt_destroy(struct ttm_tt *ttm)
> ttm->func->destroy(ttm);
> }
>
> -int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
> - unsigned long size, uint32_t page_flags)
> +void ttm_tt_init_fields(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
> + unsigned long size, uint32_t page_flags)
> {
> ttm->bdev = bdev;
> ttm->num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
> @@ -236,6 +246,12 @@ int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
> ttm->page_flags = page_flags;
> ttm->state = tt_unpopulated;
> ttm->swap_storage = NULL;
> +}
> +
> +int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
> + unsigned long size, uint32_t page_flags)
> +{
> + ttm_tt_init_fields(ttm, bdev, size, page_flags);
>
> if (ttm_tt_alloc_page_directory(ttm)) {
> ttm_tt_destroy(ttm);
> @@ -258,12 +274,7 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,
> {
> struct ttm_tt *ttm = &ttm_dma->ttm;
>
> - ttm->bdev = bdev;
> - ttm->num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
> - ttm->caching_state = tt_cached;
> - ttm->page_flags = page_flags;
> - ttm->state = tt_unpopulated;
> - ttm->swap_storage = NULL;
> + ttm_tt_init_fields(ttm, bdev, size, page_flags);
>
> INIT_LIST_HEAD(&ttm_dma->pages_list);
> if (ttm_dma_tt_alloc_page_directory(ttm_dma)) {
> @@ -275,11 +286,36 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,
> }
> EXPORT_SYMBOL(ttm_dma_tt_init);
>
> +int ttm_sg_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,
> + unsigned long size, uint32_t page_flags)
> +{
> + struct ttm_tt *ttm = &ttm_dma->ttm;
> + int ret;
> +
> + ttm_tt_init_fields(ttm, bdev, size, page_flags);
> +
> + INIT_LIST_HEAD(&ttm_dma->pages_list);
> + if (page_flags & TTM_PAGE_FLAG_SG)
> + ret = ttm_sg_tt_alloc_page_directory(ttm_dma);
> + else
> + ret = ttm_dma_tt_alloc_page_directory(ttm_dma);
> + if (ret) {
> + ttm_tt_destroy(ttm);
> + pr_err("Failed allocating page table\n");
> + return -ENOMEM;
> + }
> + return 0;
> +}
> +EXPORT_SYMBOL(ttm_sg_tt_init);
> +
> void ttm_dma_tt_fini(struct ttm_dma_tt *ttm_dma)
> {
> struct ttm_tt *ttm = &ttm_dma->ttm;
>
> - kvfree(ttm->pages);
> + if (ttm->pages)
> + kvfree(ttm->pages);
> + else
> + kvfree(ttm_dma->dma_address);
> ttm->pages = NULL;
> ttm_dma->dma_address = NULL;
> }
> diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
> index 9c78556b488e..1cf316a4257c 100644
> --- a/include/drm/ttm/ttm_tt.h
> +++ b/include/drm/ttm/ttm_tt.h
> @@ -163,6 +163,8 @@ int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
> unsigned long size, uint32_t page_flags);
> int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,
> unsigned long size, uint32_t page_flags);
> +int ttm_sg_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device *bdev,
> + unsigned long size, uint32_t page_flags);
>
> /**
> * ttm_tt_fini
