[PATCH 0/2] videobuf2-dma-sg: Contiguos memory allocation

[PATCH 0/2] videobuf2-dma-sg: Contiguos memory allocation

[Ricardo Ribalda Delgado]

Allocate memory as contiguos as possible to support dma engines with limitated amount of sg-descriptors.

Replace private structer vb2_dma_sg_desc with generic struct sg_table.

PS: This series of patches is the evolution of my previous patch for vb2-dma-sg to allocate the memory as contiguos as possible.

v3: Constains feedback from Andre Heider
Andre: Fix error handling (--pages) was wrongly fixed

v2: Contains feedback from Andre Heider and Sylwester Nawrocki

Andre: Fix error handling (--pages)
Sylwester: Squash p3 and p4 into p2

Ricardo Ribalda Delgado (2):
  videobuf2-dma-sg: Allocate pages as contiguous as possible
  videobuf2-dma-sg: Replace vb2_dma_sg_desc with sg_table

 drivers/media/platform/marvell-ccic/mcam-core.c    |   14 +-
 drivers/media/v4l2-core/videobuf2-dma-sg.c         |  149 +++++++++++---------
 drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c |   20 +--
 include/media/videobuf2-dma-sg.h                   |   10 +-
 4 files changed, 105 insertions(+), 88 deletions(-)

-- 
1.7.10.4

[PATCH v3 1/2] videobuf2-dma-sg: Allocate pages as contiguous as possible

[Ricardo Ribalda Delgado]

Most DMA engines have limitations regarding the number of DMA segments
(sg-buffers) that they can handle. Videobuffers can easily spread
through houndreds of pages.

In the previous aproach, the pages were allocated individually, this
could led to the creation houndreds of dma segments (sg-buffers) that
could not be handled by some DMA engines.

This patch tries to minimize the number of DMA segments by using
alloc_pages. In the worst case it will behave as before, but most
of the times it will reduce the number of dma segments

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
 drivers/media/v4l2-core/videobuf2-dma-sg.c |   60 +++++++++++++++++++++++-----
 1 file changed, 49 insertions(+), 11 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
index 16ae3dc..4a7b59b 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
@@ -42,10 +42,55 @@ struct vb2_dma_sg_buf {
 
 static void vb2_dma_sg_put(void *buf_priv);
 
+static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
+		gfp_t gfp_flags)
+{
+	unsigned int last_page = 0;
+	int size = buf->sg_desc.size;
+
+	while (size > 0) {
+		struct page *pages;
+		int order;
+		int i;
+
+		order = get_order(size);
+		/* Dont over allocate*/
+		if ((PAGE_SIZE << order) > size)
+			order--;
+
+		pages = NULL;
+		while (!pages) {
+			pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
+					__GFP_NOWARN | gfp_flags, order);
+			if (pages)
+				break;
+
+			if (order == 0) {
+				while (last_page--)
+					__free_page(buf->pages[last_page]);
+				return -ENOMEM;
+			}
+			order--;
+		}
+
+		split_page(pages, order);
+		for (i = 0; i < (1<<order); i++) {
+			buf->pages[last_page] = pages[i];
+			sg_set_page(&buf->sg_desc.sglist[last_page],
+					buf->pages[last_page], PAGE_SIZE, 0);
+			last_page++;
+		}
+
+		size -= PAGE_SIZE << order;
+	}
+
+	return 0;
+}
+
 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
 {
 	struct vb2_dma_sg_buf *buf;
-	int i;
+	int ret;
 
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
@@ -69,14 +114,9 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 	if (!buf->pages)
 		goto fail_pages_array_alloc;
 
-	for (i = 0; i < buf->sg_desc.num_pages; ++i) {
-		buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO |
-					   __GFP_NOWARN | gfp_flags);
-		if (NULL == buf->pages[i])
-			goto fail_pages_alloc;
-		sg_set_page(&buf->sg_desc.sglist[i],
-			    buf->pages[i], PAGE_SIZE, 0);
-	}
+	ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
+	if (ret)
+		goto fail_pages_alloc;
 
 	buf->handler.refcount = &buf->refcount;
 	buf->handler.put = vb2_dma_sg_put;
@@ -89,8 +129,6 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 	return buf;
 
 fail_pages_alloc:
-	while (--i >= 0)
-		__free_page(buf->pages[i]);
 	kfree(buf->pages);
 
 fail_pages_array_alloc:
-- 
1.7.10.4

[PATCH v3 2/2] videobuf2-dma-sg: Replace vb2_dma_sg_desc with sg_table

[Ricardo Ribalda Delgado]

Replace the private struct vb2_dma_sg_desc with the struct sg_table so
we can benefit from all the helping functions in lib/scatterlist.c for
things like allocating the sg or compacting the descriptor

marvel-ccic and solo6x10 drivers, that uses this api has been updated

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---
 drivers/media/platform/marvell-ccic/mcam-core.c    |   14 +--
 drivers/media/v4l2-core/videobuf2-dma-sg.c         |  103 ++++++++------------
 drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c |   20 ++--
 include/media/videobuf2-dma-sg.h                   |   10 +-
 4 files changed, 63 insertions(+), 84 deletions(-)

diff --git a/drivers/media/platform/marvell-ccic/mcam-core.c b/drivers/media/platform/marvell-ccic/mcam-core.c
index 64ab91e..0ac51bd 100644
--- a/drivers/media/platform/marvell-ccic/mcam-core.c
+++ b/drivers/media/platform/marvell-ccic/mcam-core.c
@@ -1040,16 +1040,16 @@ static int mcam_vb_sg_buf_prepare(struct vb2_buffer *vb)
 {
 	struct mcam_vb_buffer *mvb = vb_to_mvb(vb);
 	struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
-	struct vb2_dma_sg_desc *sgd = vb2_dma_sg_plane_desc(vb, 0);
+	struct sg_table *sg_table = vb2_dma_sg_plane_desc(vb, 0);
 	struct mcam_dma_desc *desc = mvb->dma_desc;
 	struct scatterlist *sg;
 	int i;
 
-	mvb->dma_desc_nent = dma_map_sg(cam->dev, sgd->sglist, sgd->num_pages,
-			DMA_FROM_DEVICE);
+	mvb->dma_desc_nent = dma_map_sg(cam->dev, sg_table->sgl,
+			sg_table->nents, DMA_FROM_DEVICE);
 	if (mvb->dma_desc_nent <= 0)
 		return -EIO;  /* Not sure what's right here */
-	for_each_sg(sgd->sglist, sg, mvb->dma_desc_nent, i) {
+	for_each_sg(sg_table->sgl, sg, mvb->dma_desc_nent, i) {
 		desc->dma_addr = sg_dma_address(sg);
 		desc->segment_len = sg_dma_len(sg);
 		desc++;
@@ -1060,9 +1060,11 @@ static int mcam_vb_sg_buf_prepare(struct vb2_buffer *vb)
 static int mcam_vb_sg_buf_finish(struct vb2_buffer *vb)
 {
 	struct mcam_camera *cam = vb2_get_drv_priv(vb->vb2_queue);
-	struct vb2_dma_sg_desc *sgd = vb2_dma_sg_plane_desc(vb, 0);
+	struct sg_table *sg_table = vb2_dma_sg_plane_desc(vb, 0);
 
-	dma_unmap_sg(cam->dev, sgd->sglist, sgd->num_pages, DMA_FROM_DEVICE);
+	if (sg_table)
+		dma_unmap_sg(cam->dev, sg_table->sgl,
+				sg_table->nents, DMA_FROM_DEVICE);
 	return 0;
 }
 
diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
index 4a7b59b..0328899 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
@@ -35,7 +35,9 @@ struct vb2_dma_sg_buf {
 	struct page			**pages;
 	int				write;
 	int				offset;
-	struct vb2_dma_sg_desc		sg_desc;
+	struct sg_table			sg_table;
+	size_t				size;
+	unsigned int			num_pages;
 	atomic_t			refcount;
 	struct vb2_vmarea_handler	handler;
 };
@@ -46,7 +48,7 @@ static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
 		gfp_t gfp_flags)
 {
 	unsigned int last_page = 0;
-	int size = buf->sg_desc.size;
+	int size = buf->size;
 
 	while (size > 0) {
 		struct page *pages;
@@ -74,12 +76,8 @@ static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
 		}
 
 		split_page(pages, order);
-		for (i = 0; i < (1<<order); i++) {
-			buf->pages[last_page] = pages[i];
-			sg_set_page(&buf->sg_desc.sglist[last_page],
-					buf->pages[last_page], PAGE_SIZE, 0);
-			last_page++;
-		}
+		for (i = 0; i < (1<<order); i++)
+			buf->pages[last_page++] = pages[i];
 
 		size -= PAGE_SIZE << order;
 	}
@@ -91,6 +89,7 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 {
 	struct vb2_dma_sg_buf *buf;
 	int ret;
+	int num_pages;
 
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
@@ -99,17 +98,11 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 	buf->vaddr = NULL;
 	buf->write = 0;
 	buf->offset = 0;
-	buf->sg_desc.size = size;
+	buf->size = size;
 	/* size is already page aligned */
-	buf->sg_desc.num_pages = size >> PAGE_SHIFT;
-
-	buf->sg_desc.sglist = vzalloc(buf->sg_desc.num_pages *
-				      sizeof(*buf->sg_desc.sglist));
-	if (!buf->sg_desc.sglist)
-		goto fail_sglist_alloc;
-	sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
+	buf->num_pages = size >> PAGE_SHIFT;
 
-	buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
+	buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 			     GFP_KERNEL);
 	if (!buf->pages)
 		goto fail_pages_array_alloc;
@@ -118,6 +111,11 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 	if (ret)
 		goto fail_pages_alloc;
 
+	ret = sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
+			buf->num_pages, 0, size, gfp_flags);
+	if (ret)
+		goto fail_table_alloc;
+
 	buf->handler.refcount = &buf->refcount;
 	buf->handler.put = vb2_dma_sg_put;
 	buf->handler.arg = buf;
@@ -125,16 +123,16 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 	atomic_inc(&buf->refcount);
 
 	dprintk(1, "%s: Allocated buffer of %d pages\n",
-		__func__, buf->sg_desc.num_pages);
+		__func__, buf->num_pages);
 	return buf;
 
+fail_table_alloc:
+	num_pages = buf->num_pages;
+	while (num_pages--)
+		__free_page(buf->pages[num_pages]);
 fail_pages_alloc:
 	kfree(buf->pages);
-
 fail_pages_array_alloc:
-	vfree(buf->sg_desc.sglist);
-
-fail_sglist_alloc:
 	kfree(buf);
 	return NULL;
 }
@@ -142,14 +140,14 @@ fail_sglist_alloc:
 static void vb2_dma_sg_put(void *buf_priv)
 {
 	struct vb2_dma_sg_buf *buf = buf_priv;
-	int i = buf->sg_desc.num_pages;
+	int i = buf->num_pages;
 
 	if (atomic_dec_and_test(&buf->refcount)) {
 		dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
-			buf->sg_desc.num_pages);
+			buf->num_pages);
 		if (buf->vaddr)
-			vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
-		vfree(buf->sg_desc.sglist);
+			vm_unmap_ram(buf->vaddr, buf->num_pages);
+		sg_free_table(&buf->sg_table);
 		while (--i >= 0)
 			__free_page(buf->pages[i]);
 		kfree(buf->pages);
@@ -162,7 +160,7 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 {
 	struct vb2_dma_sg_buf *buf;
 	unsigned long first, last;
-	int num_pages_from_user, i;
+	int num_pages_from_user;
 
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
@@ -171,56 +169,41 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	buf->vaddr = NULL;
 	buf->write = write;
 	buf->offset = vaddr & ~PAGE_MASK;
-	buf->sg_desc.size = size;
+	buf->size = size;
 
 	first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
 	last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
-	buf->sg_desc.num_pages = last - first + 1;
-
-	buf->sg_desc.sglist = vzalloc(
-		buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
-	if (!buf->sg_desc.sglist)
-		goto userptr_fail_sglist_alloc;
+	buf->num_pages = last - first + 1;
 
-	sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
-
-	buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
+	buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 			     GFP_KERNEL);
 	if (!buf->pages)
-		goto userptr_fail_pages_array_alloc;
+		return NULL;
 
 	num_pages_from_user = get_user_pages(current, current->mm,
 					     vaddr & PAGE_MASK,
-					     buf->sg_desc.num_pages,
+					     buf->num_pages,
 					     write,
 					     1, /* force */
 					     buf->pages,
 					     NULL);
 
-	if (num_pages_from_user != buf->sg_desc.num_pages)
+	if (num_pages_from_user != buf->num_pages)
 		goto userptr_fail_get_user_pages;
 
-	sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
-		    PAGE_SIZE - buf->offset, buf->offset);
-	size -= PAGE_SIZE - buf->offset;
-	for (i = 1; i < buf->sg_desc.num_pages; ++i) {
-		sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
-			    min_t(size_t, PAGE_SIZE, size), 0);
-		size -= min_t(size_t, PAGE_SIZE, size);
-	}
+	if (sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
+			buf->num_pages, buf->offset, size, 0))
+		goto userptr_fail_alloc_table_from_pages;
+
 	return buf;
 
+userptr_fail_alloc_table_from_pages:
 userptr_fail_get_user_pages:
 	dprintk(1, "get_user_pages requested/got: %d/%d]\n",
-	       num_pages_from_user, buf->sg_desc.num_pages);
+	       num_pages_from_user, buf->num_pages);
 	while (--num_pages_from_user >= 0)
 		put_page(buf->pages[num_pages_from_user]);
 	kfree(buf->pages);
-
-userptr_fail_pages_array_alloc:
-	vfree(buf->sg_desc.sglist);
-
-userptr_fail_sglist_alloc:
 	kfree(buf);
 	return NULL;
 }
@@ -232,18 +215,18 @@ userptr_fail_sglist_alloc:
 static void vb2_dma_sg_put_userptr(void *buf_priv)
 {
 	struct vb2_dma_sg_buf *buf = buf_priv;
-	int i = buf->sg_desc.num_pages;
+	int i = buf->num_pages;
 
 	dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
-	       __func__, buf->sg_desc.num_pages);
+	       __func__, buf->num_pages);
 	if (buf->vaddr)
-		vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
+		vm_unmap_ram(buf->vaddr, buf->num_pages);
+	sg_free_table(&buf->sg_table);
 	while (--i >= 0) {
 		if (buf->write)
 			set_page_dirty_lock(buf->pages[i]);
 		put_page(buf->pages[i]);
 	}
-	vfree(buf->sg_desc.sglist);
 	kfree(buf->pages);
 	kfree(buf);
 }
@@ -256,7 +239,7 @@ static void *vb2_dma_sg_vaddr(void *buf_priv)
 
 	if (!buf->vaddr)
 		buf->vaddr = vm_map_ram(buf->pages,
-					buf->sg_desc.num_pages,
+					buf->num_pages,
 					-1,
 					PAGE_KERNEL);
 
@@ -312,7 +295,7 @@ static void *vb2_dma_sg_cookie(void *buf_priv)
 {
 	struct vb2_dma_sg_buf *buf = buf_priv;
 
-	return &buf->sg_desc;
+	return &buf->sg_table;
 }
 
 const struct vb2_mem_ops vb2_dma_sg_memops = {
diff --git a/drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c b/drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c
index 98e2902..cfa01f1 100644
--- a/drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c
+++ b/drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c
@@ -346,7 +346,7 @@ static int enc_get_mpeg_dma(struct solo_dev *solo_dev, dma_addr_t dma,
 /* Build a descriptor queue out of an SG list and send it to the P2M for
  * processing. */
 static int solo_send_desc(struct solo_enc_dev *solo_enc, int skip,
-			  struct vb2_dma_sg_desc *vbuf, int off, int size,
+			  struct sg_table *vbuf, int off, int size,
 			  unsigned int base, unsigned int base_size)
 {
 	struct solo_dev *solo_dev = solo_enc->solo_dev;
@@ -359,7 +359,7 @@ static int solo_send_desc(struct solo_enc_dev *solo_enc, int skip,
 
 	solo_enc->desc_count = 1;
 
-	for_each_sg(vbuf->sglist, sg, vbuf->num_pages, i) {
+	for_each_sg(vbuf->sgl, sg, vbuf->nents, i) {
 		struct solo_p2m_desc *desc;
 		dma_addr_t dma;
 		int len;
@@ -434,7 +434,7 @@ static int solo_fill_jpeg(struct solo_enc_dev *solo_enc,
 		struct vb2_buffer *vb, struct vop_header *vh)
 {
 	struct solo_dev *solo_dev = solo_enc->solo_dev;
-	struct vb2_dma_sg_desc *vbuf = vb2_dma_sg_plane_desc(vb, 0);
+	struct sg_table *vbuf = vb2_dma_sg_plane_desc(vb, 0);
 	int frame_size;
 	int ret;
 
@@ -443,7 +443,7 @@ static int solo_fill_jpeg(struct solo_enc_dev *solo_enc,
 	if (vb2_plane_size(vb, 0) < vh->jpeg_size + solo_enc->jpeg_len)
 		return -EIO;
 
-	sg_copy_from_buffer(vbuf->sglist, vbuf->num_pages,
+	sg_copy_from_buffer(vbuf->sgl, vbuf->nents,
 			solo_enc->jpeg_header,
 			solo_enc->jpeg_len);
 
@@ -451,12 +451,12 @@ static int solo_fill_jpeg(struct solo_enc_dev *solo_enc,
 		& ~(DMA_ALIGN - 1);
 	vb2_set_plane_payload(vb, 0, vh->jpeg_size + solo_enc->jpeg_len);
 
-	dma_map_sg(&solo_dev->pdev->dev, vbuf->sglist, vbuf->num_pages,
+	dma_map_sg(&solo_dev->pdev->dev, vbuf->sgl, vbuf->nents,
 			DMA_FROM_DEVICE);
 	ret = solo_send_desc(solo_enc, solo_enc->jpeg_len, vbuf, vh->jpeg_off,
 			frame_size, SOLO_JPEG_EXT_ADDR(solo_dev),
 			SOLO_JPEG_EXT_SIZE(solo_dev));
-	dma_unmap_sg(&solo_dev->pdev->dev, vbuf->sglist, vbuf->num_pages,
+	dma_unmap_sg(&solo_dev->pdev->dev, vbuf->sgl, vbuf->nents,
 			DMA_FROM_DEVICE);
 	return ret;
 }
@@ -465,7 +465,7 @@ static int solo_fill_mpeg(struct solo_enc_dev *solo_enc,
 		struct vb2_buffer *vb, struct vop_header *vh)
 {
 	struct solo_dev *solo_dev = solo_enc->solo_dev;
-	struct vb2_dma_sg_desc *vbuf = vb2_dma_sg_plane_desc(vb, 0);
+	struct sg_table *vbuf = vb2_dma_sg_plane_desc(vb, 0);
 	int frame_off, frame_size;
 	int skip = 0;
 	int ret;
@@ -475,7 +475,7 @@ static int solo_fill_mpeg(struct solo_enc_dev *solo_enc,
 
 	/* If this is a key frame, add extra header */
 	if (!vh->vop_type) {
-		sg_copy_from_buffer(vbuf->sglist, vbuf->num_pages,
+		sg_copy_from_buffer(vbuf->sgl, vbuf->nents,
 				solo_enc->vop,
 				solo_enc->vop_len);
 
@@ -494,12 +494,12 @@ static int solo_fill_mpeg(struct solo_enc_dev *solo_enc,
 	frame_size = (vh->mpeg_size + skip + (DMA_ALIGN - 1))
 		& ~(DMA_ALIGN - 1);
 
-	dma_map_sg(&solo_dev->pdev->dev, vbuf->sglist, vbuf->num_pages,
+	dma_map_sg(&solo_dev->pdev->dev, vbuf->sgl, vbuf->nents,
 			DMA_FROM_DEVICE);
 	ret = solo_send_desc(solo_enc, skip, vbuf, frame_off, frame_size,
 			SOLO_MP4E_EXT_ADDR(solo_dev),
 			SOLO_MP4E_EXT_SIZE(solo_dev));
-	dma_unmap_sg(&solo_dev->pdev->dev, vbuf->sglist, vbuf->num_pages,
+	dma_unmap_sg(&solo_dev->pdev->dev, vbuf->sgl, vbuf->nents,
 			DMA_FROM_DEVICE);
 	return ret;
 }
diff --git a/include/media/videobuf2-dma-sg.h b/include/media/videobuf2-dma-sg.h
index 0038526..7b89852 100644
--- a/include/media/videobuf2-dma-sg.h
+++ b/include/media/videobuf2-dma-sg.h
@@ -15,16 +15,10 @@
 
 #include <media/videobuf2-core.h>
 
-struct vb2_dma_sg_desc {
-	unsigned long		size;
-	unsigned int		num_pages;
-	struct scatterlist	*sglist;
-};
-
-static inline struct vb2_dma_sg_desc *vb2_dma_sg_plane_desc(
+static inline struct sg_table *vb2_dma_sg_plane_desc(
 		struct vb2_buffer *vb, unsigned int plane_no)
 {
-	return (struct vb2_dma_sg_desc *)vb2_plane_cookie(vb, plane_no);
+	return (struct sg_table *)vb2_plane_cookie(vb, plane_no);
 }
 
 extern const struct vb2_mem_ops vb2_dma_sg_memops;
-- 
1.7.10.4

[PATCH 0/2] videobuf2-dma-sg: Contiguos memory allocation

[Ricardo Ribalda Delgado]

Allocate memory as contiguos as possible to support dma engines with limitated amount of sg-descriptors.

Replace private structer vb2_dma_sg_desc with generic struct sg_table.

PS: This series of patches is the evolution of my previous patch for vb2-dma-sg to allocate the memory as contiguos as possible.

v2: Contains feedback from Andre Heider and Sylwester Nawrocki

Andre: Fix error handling (--pages)
Sylwester: Squash p3 and p4 into p2

Ricardo Ribalda Delgado (2):
  videobuf2-dma-sg: Allocate pages as contiguous as possible
  videobuf2-dma-sg: Replace vb2_dma_sg_desc with sg_table

 drivers/media/platform/marvell-ccic/mcam-core.c    |   14 +-
 drivers/media/v4l2-core/videobuf2-dma-sg.c         |  149 +++++++++++---------
 drivers/staging/media/solo6x10/solo6x10-v4l2-enc.c |   20 +--
 include/media/videobuf2-dma-sg.h                   |   10 +-
 4 files changed, 105 insertions(+), 88 deletions(-)

-- 
1.7.10.4