Hi Hans,
Thank you for the patch.
On Fri, Nov 7, 2014 at 5:50 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> From: Hans Verkuil <hansverk@xxxxxxxxx>
>
> Add DMABUF export support to vb2-dma-sg.
I think we should mention in the subject that this adds dmabuf export to dma-sg.
> Signed-off-by: Hans Verkuil <hansverk@xxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-dma-sg.c | 170 +++++++++++++++++++++++++++++
> 1 file changed, 170 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> index 2795c27..ca28a50 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> @@ -407,6 +407,175 @@ static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
> }
>
> /*********************************************/
> +/* DMABUF ops for exporters */
> +/*********************************************/
> +
> +struct vb2_dma_sg_attachment {
> + struct sg_table sgt;
> + enum dma_data_direction dir;
> +};
> +
> +static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
> + struct dma_buf_attachment *dbuf_attach)
> +{
> + struct vb2_dma_sg_attachment *attach;
> + unsigned int i;
> + struct scatterlist *rd, *wr;
> + struct sg_table *sgt;
> + struct vb2_dma_sg_buf *buf = dbuf->priv;
> + int ret;
> +
> + attach = kzalloc(sizeof(*attach), GFP_KERNEL);
> + if (!attach)
> + return -ENOMEM;
> +
> + sgt = &attach->sgt;
> + /* Copy the buf->base_sgt scatter list to the attachment, as we can't
> + * map the same scatter list to multiple attachments at the same time.
> + */
> + ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
> + if (ret) {
> + kfree(attach);
> + return -ENOMEM;
> + }
> +
> + rd = buf->dma_sgt->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);
> + }
> +
> + attach->dir = DMA_NONE;
> + dbuf_attach->priv = attach;
> +
> + return 0;
> +}
> +
> +static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
> + struct dma_buf_attachment *db_attach)
> +{
> + struct vb2_dma_sg_attachment *attach = db_attach->priv;
> + struct sg_table *sgt;
> +
> + if (!attach)
> + return;
> +
> + sgt = &attach->sgt;
> +
> + /* release the scatterlist cache */
> + if (attach->dir != DMA_NONE)
> + dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
> + attach->dir);
> + sg_free_table(sgt);
> + kfree(attach);
> + db_attach->priv = NULL;
> +}
> +
> +static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
> + struct dma_buf_attachment *db_attach, enum dma_data_direction dir)
> +{
> + struct vb2_dma_sg_attachment *attach = db_attach->priv;
> + /* stealing dmabuf mutex to serialize map/unmap operations */
> + struct mutex *lock = &db_attach->dmabuf->lock;
> + struct sg_table *sgt;
> + int ret;
> +
> + mutex_lock(lock);
> +
> + sgt = &attach->sgt;
> + /* return previously mapped sg table */
> + if (attach->dir == dir) {
> + mutex_unlock(lock);
> + return sgt;
> + }
> +
> + /* release any previous cache */
> + if (attach->dir != DMA_NONE) {
> + dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
> + attach->dir);
> + attach->dir = DMA_NONE;
> + }
> +
> + /* mapping to the client with new direction */
> + ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dir);
> + if (ret <= 0) {
> + pr_err("failed to map scatterlist\n");
> + mutex_unlock(lock);
> + return ERR_PTR(-EIO);
> + }
> +
> + attach->dir = dir;
> +
> + mutex_unlock(lock);
> +
> + return sgt;
> +}
> +
> +static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
> + struct sg_table *sgt, enum dma_data_direction dir)
> +{
> + /* nothing to be done here */
> +}
> +
> +static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
> +{
> + /* drop reference obtained in vb2_dma_sg_get_dmabuf */
> + vb2_dma_sg_put(dbuf->priv);
> +}
> +
> +static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
> +{
> + struct vb2_dma_sg_buf *buf = dbuf->priv;
> +
> + return buf->vaddr + pgnum * PAGE_SIZE;
As opposed to contig, which assigns vaddr on alloc(), vaddr can very
well be NULL here for sg.
--
Best regards,
Pawel Osciak
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