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[RFC 04/13] v4l: vb2-dma-contig: add setup of sglist for MMAP buffers



This patch adds the setup of sglist list for MMAP buffers.
It is needed for buffer exporting via DMABUF mechanism.

This patch depends on dma_get_pages extension to DMA api.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
 drivers/media/video/videobuf2-dma-contig.c |   51 ++++++++++++++++++++++++++-
 1 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c
index f4df9e2..0cdcd2b 100644
--- a/drivers/media/video/videobuf2-dma-contig.c
+++ b/drivers/media/video/videobuf2-dma-contig.c
@@ -31,6 +31,7 @@ struct vb2_dc_buf {
 	/* MMAP related */
 	struct vb2_vmarea_handler	handler;
 	atomic_t			refcount;
+	struct sg_table			*sgt_base;
 
 	/* USERPTR related */
 	struct vm_area_struct		*vma;
@@ -189,6 +190,7 @@ static void vb2_dc_put(void *buf_priv)
 	if (!atomic_dec_and_test(&buf->refcount))
 		return;
 
+	vb2_dc_release_sgtable(buf->sgt_base);
 	dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
 	kfree(buf);
 }
@@ -197,6 +199,9 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
 {
 	struct device *dev = alloc_ctx;
 	struct vb2_dc_buf *buf;
+	int ret = -ENOMEM;
+	int n_pages;
+	struct page **pages = NULL;
 
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
@@ -205,10 +210,41 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
 	buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr, GFP_KERNEL);
 	if (!buf->vaddr) {
 		dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
-		kfree(buf);
-		return ERR_PTR(-ENOMEM);
+		goto fail_buf;
+	}
+
+	WARN_ON((unsigned long)buf->vaddr & ~PAGE_MASK);
+	WARN_ON(buf->dma_addr & ~PAGE_MASK);
+
+	n_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+	pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
+	if (!pages) {
+		dev_err(dev, "failed to alloc page table\n");
+		goto fail_dma;
+	}
+
+	ret = dma_get_pages(dev, buf->vaddr, buf->dma_addr, pages, n_pages);
+	if (ret < 0) {
+		dev_err(dev, "failed to get buffer pages from DMA API\n");
+		goto fail_pages;
+	}
+	if (ret != n_pages) {
+		ret = -EFAULT;
+		dev_err(dev, "failed to get all pages from DMA API\n");
+		goto fail_pages;
 	}
 
+	buf->sgt_base = vb2_dc_pages_to_sgt(pages, n_pages, 0, 0);
+	if (IS_ERR(buf->sgt_base)) {
+		ret = PTR_ERR(buf->sgt_base);
+		dev_err(dev, "failed to prepare sg table\n");
+		goto fail_pages;
+	}
+
+	/* pages are no longer needed */
+	kfree(pages);
+
 	buf->dev = dev;
 	buf->size = size;
 
@@ -219,6 +255,17 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
 	atomic_inc(&buf->refcount);
 
 	return buf;
+
+fail_pages:
+	kfree(pages);
+
+fail_dma:
+	dma_free_coherent(dev, size, buf->vaddr, buf->dma_addr);
+
+fail_buf:
+	kfree(buf);
+
+	return ERR_PTR(ret);
 }
 
 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
-- 
1.7.5.4

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