On 09/11/2015 01:50 PM, Sakari Ailus wrote:
> The struct vb2_dc_buf contains two struct sg_table fields: sgt_base and
> dma_sgt. The former is used by DMA-BUF buffers whereas the latter is used
> by USERPTR.
>
> Unify the two, leaving dma_sgt.
>
> MMAP buffers do not need cache flushing since they have been allocated
> using dma_alloc_coherent().
I would have to see this again after it is rebased on 4.3-rc1. That will contain
Jan Kara's vb2 changes which might well affect this patch.
Are there use-cases where we want to allocate non-coherent memory? I know we
don't support this today, but is this something we might want in the future?
Just curious.
Hans
>
> Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-dma-contig.c | 21 ++++++++++-----------
> 1 file changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> index 94c1e64..26a0a0f 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> @@ -36,7 +36,6 @@ struct vb2_dc_buf {
> /* MMAP related */
> struct vb2_vmarea_handler handler;
> atomic_t refcount;
> - struct sg_table *sgt_base;
>
> /* USERPTR related */
> struct vm_area_struct *vma;
> @@ -117,7 +116,7 @@ static void vb2_dc_prepare(void *buf_priv)
> struct sg_table *sgt = buf->dma_sgt;
>
> /* DMABUF exporter will flush the cache for us */
> - if (!sgt || buf->db_attach)
> + if (!buf->vma)
> return;
>
> dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> @@ -129,7 +128,7 @@ static void vb2_dc_finish(void *buf_priv)
> struct sg_table *sgt = buf->dma_sgt;
>
> /* DMABUF exporter will flush the cache for us */
> - if (!sgt || buf->db_attach)
> + if (!buf->vma)
> return;
>
> dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> @@ -146,9 +145,9 @@ static void vb2_dc_put(void *buf_priv)
> if (!atomic_dec_and_test(&buf->refcount))
> return;
>
> - if (buf->sgt_base) {
> - sg_free_table(buf->sgt_base);
> - kfree(buf->sgt_base);
> + if (buf->dma_sgt) {
> + sg_free_table(buf->dma_sgt);
> + kfree(buf->dma_sgt);
> }
> dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
> put_device(buf->dev);
> @@ -252,13 +251,13 @@ static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
> /* 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->sgt_base->orig_nents, GFP_KERNEL);
> + ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
> if (ret) {
> kfree(attach);
> return -ENOMEM;
> }
>
> - rd = buf->sgt_base->sgl;
> + 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);
> @@ -409,10 +408,10 @@ static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
> exp_info.flags = flags;
> exp_info.priv = buf;
>
> - if (!buf->sgt_base)
> - buf->sgt_base = vb2_dc_get_base_sgt(buf);
> + if (!buf->dma_sgt)
> + buf->dma_sgt = vb2_dc_get_base_sgt(buf);
>
> - if (WARN_ON(!buf->sgt_base))
> + if (WARN_ON(!buf->dma_sgt))
> return NULL;
>
> dbuf = dma_buf_export(&exp_info);
>
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