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

Signed-off-by: Ricardo Ribalda Delgado <ricardo.riba...@gmail.com>
---
 drivers/media/v4l2-core/videobuf2-dma-sg.c |  103 ++++++++++++----------------
 include/media/videobuf2-dma-sg.h           |   10 +--
 2 files changed, 45 insertions(+), 68 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c 
b/drivers/media/v4l2-core/videobuf2-dma-sg.c
index 9bf02c3..5baf03d 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 >= 0)
+               __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/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

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