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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 at amd.com>
>> ---
>> Â drivers/gpu/drm/ttm/ttm_tt.c | 54
>> ++++++++++++++++++++++++++++++++++++--------
>>  include/drm/ttm/ttm_tt.h    | 2 ++
>> Â 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)
>> Â Â Â Â Â return 0;
>> Â }
>> Â +static int ttm_sg_tt_alloc_page_directory(struct ttm_dma_tt *ttm)
>> +{
>> +Â Â Â ttm->dma_address = kvmalloc_array(ttm->ttm.num_pages,
>> +Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â sizeof(*ttm->dma_address),
>> +Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â GFP_KERNEL | __GFP_ZERO);
>> +Â Â Â if (!ttm->dma_address)
>> +Â Â Â Â Â Â Â return -ENOMEM;
>> +Â Â Â return 0;
>> +}
>> +
>> Â #ifdef CONFIG_X86
>> Â static inline int ttm_tt_set_page_caching(struct page *p,
>> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â enum ttm_caching_state c_old,
>> @@ -227,8 +237,8 @@ void ttm_tt_destroy(struct ttm_tt *ttm)
>> Â Â Â Â Â ttm->func->destroy(ttm);
>> Â }
>> Â -int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
>> -Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags)
>> +void ttm_tt_init_fields(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
>> +Â Â Â Â Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags)
>> Â {
>> Â Â Â Â Â ttm->bdev = bdev;
>> Â Â Â Â Â 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,
>> Â Â Â Â Â ttm->page_flags = page_flags;
>> Â Â Â Â Â ttm->state = tt_unpopulated;
>> Â Â Â Â Â ttm->swap_storage = NULL;
>> +}
>> +
>> +int ttm_tt_init(struct ttm_tt *ttm, struct ttm_bo_device *bdev,
>> +Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags)
>> +{
>> +Â Â Â ttm_tt_init_fields(ttm, bdev, size, page_flags);
>> Â Â Â Â Â Â if (ttm_tt_alloc_page_directory(ttm)) {
>> Â Â Â Â Â Â Â Â Â ttm_tt_destroy(ttm);
>> @@ -258,12 +274,7 @@ int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma,
>> struct ttm_bo_device *bdev,
>> Â {
>> Â Â Â Â Â struct ttm_tt *ttm = &ttm_dma->ttm;
>> Â -Â Â Â ttm->bdev = bdev;
>> -Â Â Â ttm->num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
>> -Â Â Â ttm->caching_state = tt_cached;
>> -Â Â Â ttm->page_flags = page_flags;
>> -Â Â Â ttm->state = tt_unpopulated;
>> -Â Â Â ttm->swap_storage = NULL;
>> +Â Â Â ttm_tt_init_fields(ttm, bdev, size, page_flags);
>> Â Â Â Â Â Â INIT_LIST_HEAD(&ttm_dma->pages_list);
>> Â Â Â Â Â 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,
>> Â }
>> Â EXPORT_SYMBOL(ttm_dma_tt_init);
>> Â +int ttm_sg_tt_init(struct ttm_dma_tt *ttm_dma, struct
>> ttm_bo_device *bdev,
>> +Â Â Â Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags)
>> +{
>> +Â Â Â struct ttm_tt *ttm = &ttm_dma->ttm;
>> +Â Â Â int ret;
>> +
>> +Â Â Â ttm_tt_init_fields(ttm, bdev, size, page_flags);
>> +
>> +Â Â Â INIT_LIST_HEAD(&ttm_dma->pages_list);
>> +Â Â Â if (page_flags & TTM_PAGE_FLAG_SG)
>> +Â Â Â Â Â Â Â ret = ttm_sg_tt_alloc_page_directory(ttm_dma);
>> +Â Â Â else
>> +Â Â Â Â Â Â Â ret = ttm_dma_tt_alloc_page_directory(ttm_dma);
>> +Â Â Â if (ret) {
>> +Â Â Â Â Â Â Â ttm_tt_destroy(ttm);
>> +Â Â Â Â Â Â Â pr_err("Failed allocating page table\n");
>> +Â Â Â Â Â Â Â return -ENOMEM;
>> +Â Â Â }
>> +Â Â Â return 0;
>> +}
>> +EXPORT_SYMBOL(ttm_sg_tt_init);
>> +
>> Â void ttm_dma_tt_fini(struct ttm_dma_tt *ttm_dma)
>> Â {
>> Â Â Â Â Â struct ttm_tt *ttm = &ttm_dma->ttm;
>> Â -Â Â Â kvfree(ttm->pages);
>> +Â Â Â if (ttm->pages)
>> +Â Â Â Â Â Â Â kvfree(ttm->pages);
>> +Â Â Â else
>> +Â Â Â Â Â Â Â kvfree(ttm_dma->dma_address);
>> Â Â Â Â Â ttm->pages = NULL;
>> Â Â Â Â Â ttm_dma->dma_address = NULL;
>> Â }
>> 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,
>> Â Â Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags);
>> Â int ttm_dma_tt_init(struct ttm_dma_tt *ttm_dma, struct
>> ttm_bo_device *bdev,
>> Â Â Â Â Â Â Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags);
>> +int ttm_sg_tt_init(struct ttm_dma_tt *ttm_dma, struct ttm_bo_device
>> *bdev,
>> +Â Â Â Â Â Â Â Â Â Â unsigned long size, uint32_t page_flags);
>> Â Â /**
>> Â Â * ttm_tt_fini
>
