Just a small heads-up for an upcoming change...
On Tue October 2 2012 16:27:14 Tomasz Stanislawski wrote:
> From: Sumit Semwal <sumit.semwal at ti.com>
>
> This patch adds support for DMABUF memory type in videobuf2. It calls relevant
> APIs of dma_buf for v4l reqbuf / qbuf / dqbuf operations.
>
> For this version, the support is for videobuf2 as a user of the shared buffer;
> so the allocation of the buffer is done outside of V4L2. [A sample allocator
> of
> dma-buf shared buffer is given at [1]]
>
> [1]: Rob Clark's DRM:
> https://github.com/robclark/kernel-omap4/commits/drmplane-dmabuf
>
> Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
> [original work in the PoC for buffer sharing]
> Signed-off-by: Sumit Semwal <sumit.semwal at ti.com>
> Signed-off-by: Sumit Semwal <sumit.semwal at linaro.org>
> Acked-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> drivers/media/video/Kconfig | 1 +
> drivers/media/video/videobuf2-core.c | 207
> +++++++++++++++++++++++++++++++++-
> include/media/videobuf2-core.h | 27 +++++
> 3 files changed, 232 insertions(+), 3 deletions(-)
>
<snip>
> @@ -970,6 +1040,109 @@ static int __qbuf_mmap(struct vb2_buffer *vb, const
> struct v4l2_buffer *b)
> }
>
> /**
> + * __qbuf_dmabuf() - handle qbuf of a DMABUF buffer
> + */
> +static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> +{
> + struct v4l2_plane planes[VIDEO_MAX_PLANES];
> + struct vb2_queue *q = vb->vb2_queue;
> + void *mem_priv;
> + unsigned int plane;
> + int ret;
> + int write = !V4L2_TYPE_IS_OUTPUT(q->type);
> +
> + /* Verify and copy relevant information provided by the userspace */
> + ret = __fill_vb2_buffer(vb, b, planes);
Note that this code will have to change a bit when my multiplanar fixes go in:
http://www.spinics.net/lists/linux-media/msg54601.html
__fill_vb2_buffer is now a void function, so there won't be any need to check
the error.
> + if (ret)
> + return ret;
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + struct dma_buf *dbuf = dma_buf_get(planes[plane].m.fd);
> +
> + if (IS_ERR_OR_NULL(dbuf)) {
> + dprintk(1, "qbuf: invalid dmabuf fd for plane %d\n",
> + plane);
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + /* use DMABUF size if length is not provided */
> + if (planes[plane].length == 0)
> + planes[plane].length = dbuf->size;
> +
> + if (planes[plane].length < planes[plane].data_offset +
> + q->plane_sizes[plane]) {
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + /* Skip the plane if already verified */
> + if (dbuf == vb->planes[plane].dbuf &&
> + vb->v4l2_planes[plane].length == planes[plane].length) {
> + dma_buf_put(dbuf);
> + continue;
> + }
> +
> + dprintk(1, "qbuf: buffer for plane %d changed\n", plane);
> +
> + /* Release previously acquired memory if present */
> + __vb2_plane_dmabuf_put(q, &vb->planes[plane]);
> + memset(&vb->v4l2_planes[plane], 0, sizeof(struct v4l2_plane));
> +
> + /* Acquire each plane's memory */
> + mem_priv = call_memop(q, attach_dmabuf, q->alloc_ctx[plane],
> + dbuf, planes[plane].length, write);
> + if (IS_ERR(mem_priv)) {
> + dprintk(1, "qbuf: failed to attach dmabuf\n");
> + ret = PTR_ERR(mem_priv);
> + dma_buf_put(dbuf);
> + goto err;
> + }
> +
> + vb->planes[plane].dbuf = dbuf;
> + vb->planes[plane].mem_priv = mem_priv;
> + }
> +
> + /* TODO: This pins the buffer(s) with dma_buf_map_attachment()).. but
> + * really we want to do this just before the DMA, not while queueing
> + * the buffer(s)..
> + */
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + ret = call_memop(q, map_dmabuf, vb->planes[plane].mem_priv);
> + if (ret) {
> + dprintk(1, "qbuf: failed to map dmabuf for plane %d\n",
> + plane);
> + goto err;
> + }
> + vb->planes[plane].dbuf_mapped = 1;
> + }
> +
> + /*
> + * Call driver-specific initialization on the newly acquired buffer,
> + * if provided.
> + */
> + ret = call_qop(q, buf_init, vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer initialization failed\n");
> + goto err;
> + }
> +
> + /*
> + * Now that everything is in order, copy relevant information
> + * provided by userspace.
> + */
> + for (plane = 0; plane < vb->num_planes; ++plane)
> + vb->v4l2_planes[plane] = planes[plane];
> +
> + return 0;
> +err:
> + /* In case of errors, release planes that were already acquired */
> + __vb2_buf_dmabuf_put(vb);
> +
> + return ret;
> +}
