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@xxxxxxxxxxx>
---
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);
--
1.7.0.4
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