With this change, the exynos drm dmabuf module can export and import dmabuf of gem objects with non-continuous memory.
The exynos_map_dmabuf function can create SGT of a non-contiguous buffer by calling dma_get_pages to retrieve the allocated pages and then maps the SGT to the caller's address space.
Signed-off-by: Prathyush K prathyush.k@samsung.com --- drivers/gpu/drm/exynos/exynos_drm_dmabuf.c | 98 +++++++++++++++++++++++----- 1 files changed, 81 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c index cbb6ad4..54b88bd 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c +++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c @@ -56,6 +56,59 @@ static void exynos_dmabuf_detach(struct dma_buf *dmabuf, dma_buf_put(dmabuf); }
+ +static struct sg_table *drm_dc_pages_to_sgt(struct page **pages, + unsigned long n_pages, size_t offset, size_t offset2, dma_addr_t daddr) +{ + struct sg_table *sgt; + struct scatterlist *s; + int i, j, cur_page, chunks, ret; + + sgt = kzalloc(sizeof *sgt, GFP_KERNEL); + if (!sgt) + return ERR_PTR(-ENOMEM); + + /* compute number of chunks */ + chunks = 1; + for (i = 1; i < n_pages; ++i) + if (pages[i] != pages[i - 1] + 1) + ++chunks; + + ret = sg_alloc_table(sgt, chunks, GFP_KERNEL); + if (ret) { + kfree(sgt); + return ERR_PTR(-ENOMEM); + } + + /* merging chunks and putting them into the scatterlist */ + cur_page = 0; + for_each_sg(sgt->sgl, s, sgt->orig_nents, i) { + size_t size = PAGE_SIZE; + + for (j = cur_page + 1; j < n_pages; ++j) { + if (pages[j] != pages[j - 1] + 1) + break; + size += PAGE_SIZE; + } + + /* cut offset if chunk starts at the first page */ + if (cur_page == 0) + size -= offset; + /* cut offset2 if chunk ends at the last page */ + if (j == n_pages) + size -= offset2; + + sg_set_page(s, pages[cur_page], size, offset); + s->dma_address = daddr; + daddr += size; + offset = 0; + cur_page = j; + } + + return sgt; +} + + static struct sg_table *exynos_map_dmabuf(struct dma_buf_attachment *attach, enum dma_data_direction direction) { @@ -64,6 +117,8 @@ static struct sg_table *exynos_map_dmabuf(struct dma_buf_attachment *attach, struct exynos_drm_gem_buf *buffer; struct sg_table *sgt; int ret; + int size, n_pages; + struct page **pages = NULL;
DRM_DEBUG_KMS("%s\n", __FILE__);
@@ -71,27 +126,37 @@ static struct sg_table *exynos_map_dmabuf(struct dma_buf_attachment *attach,
buffer = exynos_gem_obj->buffer;
- /* TODO. consider physically non-continuous memory with IOMMU. */ + size = buffer->size; + n_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
- sgt = kzalloc(sizeof(*sgt), GFP_KERNEL); - if (!sgt) { - DRM_DEBUG_KMS("failed to allocate sg table.\n"); - return ERR_PTR(-ENOMEM); + pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL); + if (!pages) { + DRM_DEBUG_KMS("failed to alloc page table\n"); + return NULL; }
- ret = sg_alloc_table(sgt, 1, GFP_KERNEL); + ret = dma_get_pages(attach->dev, buffer->kvaddr, + buffer->dma_addr, pages, n_pages); if (ret < 0) { - DRM_DEBUG_KMS("failed to allocate scatter list.\n"); - kfree(sgt); - sgt = NULL; - return ERR_PTR(-ENOMEM); + DRM_DEBUG_KMS("failed to get buffer pages from DMA API\n"); + return NULL; } + if (ret != n_pages) { + DRM_DEBUG_KMS("failed to get all pages from DMA API\n"); + return NULL; + } + + sgt = drm_dc_pages_to_sgt(pages, n_pages, 0, 0, buffer->dma_addr); + if (IS_ERR(sgt)) { + DRM_DEBUG_KMS("failed to prepare sg table\n"); + return NULL; + } + + sgt->nents = dma_map_sg(attach->dev, sgt->sgl, + sgt->orig_nents, DMA_BIDIRECTIONAL);
- sg_init_table(sgt->sgl, 1); - sg_dma_len(sgt->sgl) = buffer->size; - sg_set_page(sgt->sgl, pfn_to_page(PFN_DOWN(buffer->dma_addr)), - buffer->size, 0); - sg_dma_address(sgt->sgl) = buffer->dma_addr; + /* pages are no longer needed */ + kfree(pages);
/* * increase reference count of this buffer. @@ -303,8 +368,6 @@ int exynos_dmabuf_prime_fd_to_handle(struct drm_device *drm_dev, if (ret < 0) goto fail_handle;
- /* consider physically non-continuous memory with IOMMU. */ - buffer->dma_addr = sg_dma_address(sgt->sgl); buffer->size = sg_dma_len(sgt->sgl);
@@ -316,6 +379,7 @@ int exynos_dmabuf_prime_fd_to_handle(struct drm_device *drm_dev, atomic_set(&buffer->shared_refcount, 1);
exynos_gem_obj->base.import_attach = attach; + exynos_gem_obj->buffer = buffer;
ret = drm_prime_insert_fd_handle_mapping(&file_priv->prime, dmabuf, *handle);