ttm: add ttm_sg_tt_init

Christian König Tue, 27 Feb 2018 04:08:07 -0800

Hi guys,

at least on amdgpu and radeon the page array allocated byttm_dma_tt_init is completely unused in the case of DMA-buf sharing. SoI'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 isNouveau. So my question is are you guys using the page array anywhere inyour kernel driver in case of a DMA-buf sharing?

If no then I could just make this the default behavior for all driversand 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.koe...@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


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

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