Hi Tomasz,
On Tuesday 13 March 2012 11:17:01 Tomasz Stanislawski wrote:
> From: Sumit Semwal <sumit.semwal@xxxxxx>
>
> 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@xxxxxx>
> Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> [author of the original patch]
> Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
> [integration with refactored dma-contig allocator]
> ---
> drivers/media/video/videobuf2-dma-contig.c | 116
> ++++++++++++++++++++++++++++ 1 files changed, 116 insertions(+), 0
> deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-dma-contig.c
> b/drivers/media/video/videobuf2-dma-contig.c index c1dc043..746dd5f 100644
> --- a/drivers/media/video/videobuf2-dma-contig.c
> +++ b/drivers/media/video/videobuf2-dma-contig.c
> @@ -35,6 +35,9 @@ struct vb2_dc_buf {
>
> /* USERPTR related */
> struct vm_area_struct *vma;
> +
> + /* DMABUF related */
> + struct dma_buf_attachment *db_attach;
> };
>
> /*********************************************/
> @@ -485,6 +488,115 @@ 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;
> + }
I've checked why dma_map_sg() was missing from here, and then remembered that
the exporter is still responsible for mapping the buffer to the importer's
device address space :-) I'll raise that topic separately.
> +
> + /* 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);
Can detach() be called with the buffer still mapped() ? Wouldn't that be a bug
in the caller ?
> +
> + /* detach this attachment */
> + dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
> + kfree(buf);
> +}
There's nothing allocator-specific in the attach/detach operations. Shouldn't
they be moved to the vb2 core ?
> +
> +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 */
> /*********************************************/
>
> @@ -498,6 +610,10 @@ 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);
--
Regards,
Laurent Pinchart
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