Re: [Linaro-mm-sig] [PATCH 08/10] v4l: vb2-dma-contig: code refactoring, support for DMABUF exporting

Em 23-01-2012 11:51, Tomasz Stanislawski escreveu:

Signed-off-by: Pawel Osciak pawel@osciak.com [author of the original file] Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com [implemetation of mmap, finish/prepare] Signed-off-by: Andrzej Pietrasiewicz andrzej.p@samsung.com [implementation of userprt handling] Signed-off-by: Sumit Semwal sumit.semwal@ti.com Signed-off-by: Sumit Semwal sumit.semwal@linaro.org [PoC for importing dmabuf buffer] Signed-off-by: Tomasz Stanislawski t.stanislaws@samsung.com [buffer exporting using dmabuf, code refactoring] Signed-off-by: Kyungmin Park kyungmin.park@samsung.com

Please provide a diff against the existing driver, in order to allow reviewing what has changed.

---

drivers/media/video/videobuf2-dma-contig.c | 762 ++++++++++++++++++++++++++++ 1 files changed, 762 insertions(+), 0 deletions(-) create mode 100644 drivers/media/video/videobuf2-dma-contig.c

diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c new file mode 100644 index 0000000..d95b23a --- /dev/null +++ b/drivers/media/video/videobuf2-dma-contig.c @@ -0,0 +1,762 @@ +/*

• • videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
• • Copyright (C) 2010 Samsung Electronics
• • Author: Pawel Osciak pawel@osciak.com
• • This program is free software; you can redistribute it and/or modify
• • it under the terms of the GNU General Public License as published by
• • the Free Software Foundation.
• */

+#include <linux/dma-buf.h> +#include <linux/dma-mapping.h> +#include <linux/module.h> +#include <linux/scatterlist.h> +#include <linux/sched.h> +#include <linux/slab.h>

+#include <media/videobuf2-core.h> +#include <media/videobuf2-memops.h>

+struct vb2_dc_buf {

• struct device *dev;
• void *vaddr;
• unsigned long size;
• dma_addr_t dma_addr;
• struct sg_table *dma_sgt;
• enum dma_data_direction dma_dir;
• /* MMAP related */
• struct vb2_vmarea_handler handler;
• atomic_t refcount;
• struct dma_buf *dma_buf;
• struct sg_table *sgt_base;
• /* USERPTR related */
• struct vm_area_struct *vma;
• /* DMABUF related */
• struct dma_buf_attachment *db_attach;

+};

+/*********************************************/ +/* scatterlist table functions */ +/*********************************************/

+static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages,

• unsigned long n_pages, size_t offset, size_t offset2)

+{

• struct sg_table *sgt;
• int i, j; /* loop counters */
• int cur_page, chunks;
• int ret;
• struct scatterlist *s;
• 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);
  

• offset = 0;
  

• cur_page = j;
  

• }
• return sgt;

+}

+static void vb2_dc_release_sgtable(struct sg_table *sgt) +{

• sg_free_table(sgt);
• kfree(sgt);

+}

+static void vb2_dc_put_sgtable(struct sg_table *sgt, int dirty) +{

• struct scatterlist *s;
• int i, j;
• for_each_sg(sgt->sgl, s, sgt->nents, i) {

• struct page *page = sg_page(s);
  

• int n_pages = PAGE_ALIGN(s->offset + s->length) >> PAGE_SHIFT;
  

• for (j = 0; j < n_pages; ++j, ++page) {
  

• 	if (dirty)
  

• 		set_page_dirty_lock(page);
  

• 	put_page(page);
  

• }
  

• }
• vb2_dc_release_sgtable(sgt);

+}

+static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt) +{

• struct scatterlist *s;
• dma_addr_t expected = sg_dma_address(sgt->sgl);
• int i;
• unsigned long size = 0;
• for_each_sg(sgt->sgl, s, sgt->nents, i) {

• if (sg_dma_address(s) != expected)
  

• 	break;
  

• expected = sg_dma_address(s) + sg_dma_len(s);
  

• size += sg_dma_len(s);
  

• }
• return size;

+}

+/*********************************************/ +/* callbacks for all buffers */ +/*********************************************/

+static void *vb2_dc_cookie(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• return &buf->dma_addr;

+}

+static void *vb2_dc_vaddr(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• return buf->vaddr;

+}

+static unsigned int vb2_dc_num_users(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• return atomic_read(&buf->refcount);

+}

+static void vb2_dc_prepare(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• struct sg_table *sgt = buf->dma_sgt;
• if (!sgt)

• return;
  

• dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);

+}

+static void vb2_dc_finish(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• struct sg_table *sgt = buf->dma_sgt;
• if (!sgt)

• return;
  

• dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);

+}

+/*********************************************/ +/* callbacks for MMAP buffers */ +/*********************************************/

+static void vb2_dc_put(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• if (!atomic_dec_and_test(&buf->refcount))

• return;
  

• if (buf->dma_buf)

• dma_buf_put(buf->dma_buf);
  

• vb2_dc_release_sgtable(buf->sgt_base);
• dma_free_coherent(buf->dev, buf->size, buf->vaddr,

• buf->dma_addr);
  

• kfree(buf);

+}

+static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size) +{

• struct device *dev = alloc_ctx;
• struct vb2_dc_buf *buf;
• int ret;
• int n_pages;
• struct page **pages = NULL;
• buf = kzalloc(sizeof *buf, GFP_KERNEL);
• if (!buf)

• return ERR_PTR(-ENOMEM);
  

• buf->dev = dev;
• buf->size = size;
• buf->vaddr = dma_alloc_coherent(buf->dev, buf->size, &buf->dma_addr,

• GFP_KERNEL);
  

• ret = -ENOMEM;
• if (!buf->vaddr) {

• dev_err(dev, "dma_alloc_coherent of size %ld failed\n",
  

• 	size);
  

• 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) {

• printk(KERN_ERR "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) {

• printk(KERN_ERR "failed to get buffer pages from DMA API\n");
  

• goto fail_pages;
  

• }
• if (ret != n_pages) {

• ret = -EFAULT;
  

• printk(KERN_ERR "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);
  

• printk(KERN_ERR "failed to prepare sg table\n");
  

• goto fail_pages;
  

• }
• /* pages are no longer needed */
• kfree(pages);
• buf->handler.refcount = &buf->refcount;
• buf->handler.put = vb2_dc_put;
• buf->handler.arg = buf;
• atomic_inc(&buf->refcount);
• return buf;

+fail_pages:

• kfree(pages);

+fail_dma:

• dma_free_coherent(buf->dev, buf->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) +{

• struct vb2_dc_buf *buf = buf_priv;
• int ret;
• /*

• * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
  

• * map whole buffer
  

• */
  

• vma->vm_pgoff = 0;
• ret = dma_mmap_writecombine(buf->dev, vma, buf->vaddr,

• buf->dma_addr, buf->size);
  

• if (ret) {

• printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
  

• return ret;
  

• }
• vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
• vma->vm_private_data = &buf->handler;
• vma->vm_ops = &vb2_common_vm_ops;
• vma->vm_ops->open(vma);
• printk(KERN_DEBUG "%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",

• __func__, (unsigned long)buf->dma_addr, vma->vm_start,
  

• buf->size);
  

• return 0;

+}

+/*********************************************/ +/* DMABUF ops for exporters */ +/*********************************************/

+struct vb2_dc_attachment {

• struct sg_table sgt;
• enum dma_data_direction dir;

+};

+static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,

• struct dma_buf_attachment *dbuf_attach)

+{

• /* nothing to be done */
• return 0;

+}

+static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,

• struct dma_buf_attachment *db_attach)

+{

• struct vb2_dc_attachment *attach = db_attach->priv;
• struct sg_table *sgt;
• if (!attach)

• return;
  

• sgt = &attach->sgt;
• dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->nents, attach->dir);
• sg_free_table(sgt);
• kfree(attach);
• db_attach->priv = NULL;

+}

+static struct sg_table *vb2_dc_dmabuf_ops_map(

• struct dma_buf_attachment *db_attach, enum dma_data_direction dir)

+{

• struct dma_buf *dbuf = db_attach->dmabuf;
• struct vb2_dc_buf *buf = dbuf->priv;
• struct vb2_dc_attachment *attach = db_attach->priv;
• struct sg_table *sgt;
• struct scatterlist *rd, *wr;
• int i, ret;
• /* return previously mapped sg table */
• if (attach)

• return &attach->sgt;
  

• attach = kzalloc(sizeof *attach, GFP_KERNEL);
• if (!attach)

• return ERR_PTR(-ENOMEM);
  

• sgt = &attach->sgt;
• attach->dir = dir;
• /* copying the buf->base_sgt to attachment */
• ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
• if (ret) {

• kfree(attach);
  

• return ERR_PTR(-ENOMEM);
  

• }
• rd = buf->sgt_base->sgl;
• wr = sgt->sgl;
• for (i = 0; i < sgt->orig_nents; ++i) {

• sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
  

• rd = sg_next(rd);
  

• wr = sg_next(wr);
  

• }
• /* mapping new sglist to the client */
• ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dir);
• if (ret <= 0) {

• printk(KERN_ERR "failed to map scatterlist\n");
  

• sg_free_table(sgt);
  

• kfree(attach);
  

• return ERR_PTR(-EIO);
  

• }
• db_attach->priv = attach;
• return sgt;

+}

+static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,

• struct sg_table *sgt)

+{

• /* nothing to be done here */

+}

+static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf) +{

• /* drop reference obtained in vb2_dc_get_dmabuf */
• vb2_dc_put(dbuf->priv);

+}

+static struct dma_buf_ops vb2_dc_dmabuf_ops = {

• .attach = vb2_dc_dmabuf_ops_attach,
• .detach = vb2_dc_dmabuf_ops_detach,
• .map_dma_buf = vb2_dc_dmabuf_ops_map,
• .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
• .release = vb2_dc_dmabuf_ops_release,

+};

+static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• struct dma_buf *dbuf;
• if (buf->dma_buf)

• return buf->dma_buf;
  

• /* dmabuf keeps reference to vb2 buffer */
• atomic_inc(&buf->refcount);
• dbuf = dma_buf_export(buf, &vb2_dc_dmabuf_ops, buf->size, 0);
• if (IS_ERR(dbuf)) {

• atomic_dec(&buf->refcount);
  

• return NULL;
  

• }
• buf->dma_buf = dbuf;
• return dbuf;

+}

+/*********************************************/ +/* callbacks for USERPTR buffers */ +/*********************************************/

+static inline int vma_is_io(struct vm_area_struct *vma) +{

• return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));

+}

+static int vb2_dc_get_pages(unsigned long start, struct page **pages,

• int n_pages, struct vm_area_struct **copy_vma, int write)

+{

• struct vm_area_struct *vma;
• int n = 0; /* number of get pages */
• int ret = -EFAULT;
• /* entering critical section for mm access */
• down_read(&current->mm->mmap_sem);
• vma = find_vma(current->mm, start);
• if (!vma) {

• printk(KERN_ERR "no vma for address %lu\n", start);
  

• goto cleanup;
  

• }
• if (vma_is_io(vma)) {

• unsigned long pfn;
  

• if (vma->vm_end - start < n_pages * PAGE_SIZE) {
  

• 	printk(KERN_ERR "vma is too small\n");
  

• 	goto cleanup;
  

• }
  

• for (n = 0; n < n_pages; ++n, start += PAGE_SIZE) {
  

• 	ret = follow_pfn(vma, start, &pfn);
  

• 	if (ret) {
  

• 		printk(KERN_ERR "no page for address %lu\n",
  

• 			start);
  

• 		goto cleanup;
  

• 	}
  

• 	pages[n] = pfn_to_page(pfn);
  

• 	get_page(pages[n]);
  

• }
  

• } else {

• n = get_user_pages(current, current->mm, start & PAGE_MASK,
  

• 	n_pages, write, 1, pages, NULL);
  

• if (n != n_pages) {
  

• 	printk(KERN_ERR "got only %d of %d user pages\n",
  

• 		n, n_pages);
  

• 	goto cleanup;
  

• }
  

• }
• *copy_vma = vb2_get_vma(vma);
• if (!*copy_vma) {

• printk(KERN_ERR "failed to copy vma\n");
  

• ret = -ENOMEM;
  

• goto cleanup;
  

• }
• /* leaving critical section for mm access */
• up_read(&current->mm->mmap_sem);
• return 0;

+cleanup:

• up_read(&current->mm->mmap_sem);
• /* putting user pages if used, can be done wothout the lock */
• while (n)

• put_page(pages[--n]);
  

• return ret;

+}

+static void vb2_dc_put_userptr(void *buf_priv) +{

• struct vb2_dc_buf *buf = buf_priv;
• struct sg_table *sgt = buf->dma_sgt;
• dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
• vb2_dc_put_sgtable(sgt, !vma_is_io(buf->vma));
• vb2_put_vma(buf->vma);
• kfree(buf);

+}

+static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,

• unsigned long size, int write)

+{

• struct vb2_dc_buf *buf;
• unsigned long start, end, offset, offset2;
• struct page **pages;
• int n_pages;
• int ret = 0;
• struct sg_table *sgt;
• unsigned long contig_size;
• buf = kzalloc(sizeof *buf, GFP_KERNEL);
• if (!buf)

• return ERR_PTR(-ENOMEM);
  

• buf->dev = alloc_ctx;
• buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
• start = (unsigned long)vaddr & PAGE_MASK;
• offset = (unsigned long)vaddr & ~PAGE_MASK;
• end = PAGE_ALIGN((unsigned long)vaddr + size);
• offset2 = end - (unsigned long)vaddr - size;
• n_pages = (end - start) >> PAGE_SHIFT;
• pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
• if (!pages) {

• ret = -ENOMEM;
  

• printk(KERN_ERR "failed to allocate pages table\n");
  

• goto fail_buf;
  

• }
• /* extract page list from userspace mapping */
• ret = vb2_dc_get_pages(start, pages, n_pages, &buf->vma, write);
• if (ret) {

• printk(KERN_ERR "failed to get user pages\n");
  

• goto fail_pages;
  

• }
• sgt = vb2_dc_pages_to_sgt(pages, n_pages, offset, offset2);
• if (!sgt) {

• printk(KERN_ERR "failed to create scatterlist table\n");
  

• ret = -ENOMEM;
  

• goto fail_get_pages;
  

• }
• /* pages are no longer needed */
• kfree(pages);
• pages = NULL;
• sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,

• buf->dma_dir);
  

• if (sgt->nents <= 0) {

• printk(KERN_ERR "failed to map scatterlist\n");
  

• ret = -EIO;
  

• goto fail_sgt;
  

• }
• contig_size = vb2_dc_get_contiguous_size(sgt);
• if (contig_size < size) {

• printk(KERN_ERR "contiguous mapping is too small %lu/%lu\n",
  

• 	contig_size, size);
  

• ret = -EFAULT;
  

• goto fail_map_sg;
  

• }
• buf->dma_addr = sg_dma_address(sgt->sgl);
• buf->size = size;
• buf->dma_sgt = sgt;
• atomic_inc(&buf->refcount);
• return buf;

+fail_map_sg:

• dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);

+fail_sgt:

• vb2_dc_put_sgtable(sgt, 0);

+fail_get_pages:

• while (pages && n_pages)

• put_page(pages[--n_pages]);
  

• vb2_put_vma(buf->vma);

+fail_pages:

• kfree(pages); /* kfree is NULL-proof */

+fail_buf:

• kfree(buf);
• return ERR_PTR(ret);

+}

+/*********************************************/ +/* callbacks for DMABUF buffers */ +/*********************************************/

+static int vb2_dc_map_dmabuf(void *mem_priv) +{

• struct vb2_dc_buf *buf = mem_priv;
• struct sg_table *sgt;
• unsigned long contig_size;
• int ret = 0;
• if (WARN_ON(!buf->db_attach)) {

• printk(KERN_ERR "trying to pin a non attached buffer\n");
  

• return -EINVAL;
  

• }
• if (WARN_ON(buf->dma_sgt)) {

• printk(KERN_ERR "dmabuf buffer is already pinned\n");
  

• return 0;
  

• }
• /* get the associated scatterlist for this buffer */
• sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
• if (IS_ERR_OR_NULL(sgt)) {

• printk(KERN_ERR "Error getting dmabuf scatterlist\n");
  

• return -EINVAL;
  

• }
• /* checking if dmabuf is big enough to store contiguous chunk */
• contig_size = vb2_dc_get_contiguous_size(sgt);
• if (contig_size < buf->size) {

• printk(KERN_ERR "contiguous chunk of dmabuf is too small\n");
  

• ret = -EFAULT;
  

• goto fail_map;
  

• }
• buf->dma_addr = sg_dma_address(sgt->sgl);
• buf->dma_sgt = sgt;
• return 0;

+fail_map:

• dma_buf_unmap_attachment(buf->db_attach, sgt);
• return ret;

+}

+static void vb2_dc_unmap_dmabuf(void *mem_priv) +{

• struct vb2_dc_buf *buf = mem_priv;
• struct sg_table *sgt = buf->dma_sgt;
• if (WARN_ON(!buf->db_attach)) {

• printk(KERN_ERR "trying to unpin a not attached buffer\n");
  

• return;
  

• }
• if (WARN_ON(!sgt)) {

• printk(KERN_ERR "dmabuf buffer is already unpinned\n");
  

• return;
  

• }
• dma_buf_unmap_attachment(buf->db_attach, sgt);
• buf->dma_addr = 0;
• buf->dma_sgt = NULL;

+}

+static void vb2_dc_detach_dmabuf(void *mem_priv) +{

• struct vb2_dc_buf *buf = mem_priv;
• if (buf->dma_addr)

• vb2_dc_unmap_dmabuf(buf);
  

• /* detach this attachment */
• dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
• kfree(buf);

+}

+static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,

• unsigned long size, int write)

+{

• struct vb2_dc_buf *buf;
• struct dma_buf_attachment *dba;
• if (dbuf->size < size)

• return ERR_PTR(-EFAULT);
  

• buf = kzalloc(sizeof *buf, GFP_KERNEL);
• if (!buf)

• return ERR_PTR(-ENOMEM);
  

• buf->dev = alloc_ctx;
• /* create attachment for the dmabuf with the user device */
• dba = dma_buf_attach(dbuf, buf->dev);
• if (IS_ERR(dba)) {

• printk(KERN_ERR "failed to attach dmabuf\n");
  

• kfree(buf);
  

• return dba;
  

• }
• buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
• buf->size = size;
• buf->db_attach = dba;
• return buf;

+}

+/*********************************************/ +/* DMA CONTIG exported functions */ +/*********************************************/

+const struct vb2_mem_ops vb2_dma_contig_memops = {

• .alloc = vb2_dc_alloc,
• .put = vb2_dc_put,
• .get_dmabuf = vb2_dc_get_dmabuf,
• .cookie = vb2_dc_cookie,
• .vaddr = vb2_dc_vaddr,
• .mmap = vb2_dc_mmap,
• .get_userptr = vb2_dc_get_userptr,
• .put_userptr = vb2_dc_put_userptr,
• .prepare = vb2_dc_prepare,
• .finish = vb2_dc_finish,
• .map_dmabuf = vb2_dc_map_dmabuf,
• .unmap_dmabuf = vb2_dc_unmap_dmabuf,
• .attach_dmabuf = vb2_dc_attach_dmabuf,
• .detach_dmabuf = vb2_dc_detach_dmabuf,
• .num_users = vb2_dc_num_users,

+}; +EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);

+void *vb2_dma_contig_init_ctx(struct device *dev) +{

• return dev;

+} +EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);

+void vb2_dma_contig_cleanup_ctx(void *alloc_ctx) +{ +} +EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);

+MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2"); +MODULE_AUTHOR("Pawel Osciak pawel@osciak.com"); +MODULE_LICENSE("GPL");