Re: [PATCH 4/5] drm/ttm: add ttm_sg_tt_init

On Mon, Mar 5, 2018 at 10:06 PM, Christian König christian.koenig@amd.com wrote:

Ping?

On a quick look, it looks like both are used sometimes. I believe this had something to do with the addition of Tegra support, but I'll need some time to look into the details of why/how these things are used again.

Ben.

Am 27.02.2018 um 13:07 schrieb Christian König:

...

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@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