Re: [Linaro-mm-sig] [PATCH 11/11] v4l: vb2: Add dma-contig allocator as dma_buf user

Hi Tomasz,

On Thursday 05 April 2012 16:00:08 Tomasz Stanislawski wrote:

From: Sumit Semwal sumit.semwal@ti.com

This patch makes changes for adding dma-contig as a dma_buf user. It provides function implementations for the {attach, detach, map, unmap}_dmabuf() mem_ops of DMABUF memory type.

Signed-off-by: Sumit Semwal sumit.semwal@ti.com Signed-off-by: Sumit Semwal sumit.semwal@linaro.org [author of the original patch] Signed-off-by: Tomasz Stanislawski t.stanislaws@samsung.com [integration with refactored dma-contig allocator]

---

drivers/media/video/videobuf2-dma-contig.c | 117 +++++++++++++++++++++++++ 1 files changed, 117 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c index 30f316588..6329483 100644 --- a/drivers/media/video/videobuf2-dma-contig.c +++ b/drivers/media/video/videobuf2-dma-contig.c @@ -10,6 +10,7 @@

• the Free Software Foundation.

*/

+#include <linux/dma-buf.h> #include <linux/module.h> #include <linux/scatterlist.h> #include <linux/sched.h> @@ -33,6 +34,9 @@ struct vb2_dc_buf {

/* USERPTR related */ struct vm_area_struct *vma;

• /* DMABUF related */
• struct dma_buf_attachment *db_attach;

};

/*********************************************/ @@ -425,6 +429,115 @@ fail_buf: }

/*********************************************/ +/* 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;
  

The fail_map label is only used here, you can move the dma_buf_unmap_attachment() call here and return -EFAULT directly.

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

+fail_map:

• dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
• 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_dir);
• 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);
  

What would you think about calling vb2_dc_unmap_dmabuf() from vb2 core instead, to keep the map/unmap calls symmetrical (the second WARN_ON and the related printk in vb2_dc_unmap_dmabuf() might need to go then) ?

• /* 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 */ /*********************************************/

@@ -438,6 +551,10 @@ const struct vb2_mem_ops vb2_dma_contig_memops = { .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);