On Tue, Mar 02, 2021 at 09:46:24AM +0900, Sergey Senozhatsky wrote:
> This adds support for new noncontiguous DMA API, which
> requires allocators to have two execution branches: one
> for the current API, and one for the new one.
>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
> [hch: untested conversion to the ne API]
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> .../common/videobuf2/videobuf2-dma-contig.c | 141 +++++++++++++++---
> 1 file changed, 117 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index 1e218bc440c6..d6a9f7b682f3 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -17,6 +17,7 @@
> #include <linux/sched.h>
> #include <linux/slab.h>
> #include <linux/dma-mapping.h>
> +#include <linux/highmem.h>
>
> #include <media/videobuf2-v4l2.h>
> #include <media/videobuf2-dma-contig.h>
> @@ -42,8 +43,14 @@ struct vb2_dc_buf {
> struct dma_buf_attachment *db_attach;
>
> struct vb2_buffer *vb;
> + unsigned int non_coherent_mem:1;
> };
>
> +static bool vb2_dc_is_coherent(struct vb2_dc_buf *buf)
> +{
> + return !buf->non_coherent_mem;
> +}
nit: Given that this is just a simple negated return, do we need a dedicated
helper for it?
> +
> /*********************************************/
> /* scatterlist table functions */
> /*********************************************/
> @@ -78,12 +85,21 @@ static void *vb2_dc_cookie(struct vb2_buffer *vb, void *buf_priv)
> static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
> {
> struct vb2_dc_buf *buf = buf_priv;
> - struct dma_buf_map map;
> - int ret;
>
> - if (!buf->vaddr && buf->db_attach) {
> - ret = dma_buf_vmap(buf->db_attach->dmabuf, &map);
> - buf->vaddr = ret ? NULL : map.vaddr;
> + if (buf->vaddr)
> + return buf->vaddr;
> +
> + if (buf->db_attach) {
> + struct dma_buf_map map;
> +
> + if (!dma_buf_vmap(buf->db_attach->dmabuf, &map))
> + buf->vaddr = map.vaddr;
> + }
> +
> + if (!vb2_dc_is_coherent(buf)) {
I believe it's not possible for both buf->db_attach and
!vb2_dc_is_coherent() to be true, but nevertheless the code can be
misleading for the reader. Would it make sense to just return early in the
if that handles db_attach?
> + buf->vaddr = dma_vmap_noncontiguous(buf->dev,
> + buf->size,
> + buf->dma_sgt);
> }
>
> return buf->vaddr;
> @@ -101,13 +117,26 @@ static void vb2_dc_prepare(void *buf_priv)
> struct vb2_dc_buf *buf = buf_priv;
> struct sg_table *sgt = buf->dma_sgt;
>
> + /* This takes care of DMABUF and user-enforced cache sync hint */
> if (buf->vb->skip_cache_sync_on_prepare)
> return;
>
> + /*
> + * Coherent MMAP buffers do not need to be synced, unlike coherent
> + * USERPTR and non-coherent MMAP buffers.
USERPTR buffers are always considered non-coherent.
> + */
> + if (buf->vb->memory == V4L2_MEMORY_MMAP && vb2_dc_is_coherent(buf))
> + return;
> +
> if (!sgt)
> return;
>
> + /* For both USERPTR and non-coherent MMAP */
> dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
> +
> + /* Non-coherrent MMAP only */
> + if (!vb2_dc_is_coherent(buf) && buf->vaddr)
> + flush_kernel_vmap_range(buf->vaddr, buf->size);
> }
>
> static void vb2_dc_finish(void *buf_priv)
> @@ -115,19 +144,46 @@ static void vb2_dc_finish(void *buf_priv)
> struct vb2_dc_buf *buf = buf_priv;
> struct sg_table *sgt = buf->dma_sgt;
>
> + /* This takes care of DMABUF and user-enforced cache sync hint */
> if (buf->vb->skip_cache_sync_on_finish)
> return;
>
> + /*
> + * Coherent MMAP buffers do not need to be synced, unlike coherent
> + * USERPTR and non-coherent MMAP buffers.
Ditto.
> + */
> + if (buf->vb->memory == V4L2_MEMORY_MMAP && vb2_dc_is_coherent(buf))
> + return;
> +
> if (!sgt)
> return;
>
> + /* For both USERPTR and non-coherent MMAP */
> dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
> +
> + /* Non-coherrent MMAP only */
> + if (!vb2_dc_is_coherent(buf) && buf->vaddr)
> + invalidate_kernel_vmap_range(buf->vaddr, buf->size);
> }
>
> /*********************************************/
> /* callbacks for MMAP buffers */
> /*********************************************/
>
> +static void __vb2_dc_put(struct vb2_dc_buf *buf)
> +{
> + if (vb2_dc_is_coherent(buf)) {
> + dma_free_attrs(buf->dev, buf->size, buf->cookie,
> + buf->dma_addr, buf->attrs);
> + return;
> + }
> +
> + if (buf->vaddr)
> + dma_vunmap_noncontiguous(buf->dev, buf->vaddr);
> + dma_free_noncontiguous(buf->dev, buf->size,
> + buf->dma_sgt, buf->dma_addr);
> +}
> +
> static void vb2_dc_put(void *buf_priv)
nit: Unrelated to this patch or series, but could be a follow-up clean-up:
Could we rename this and the newly added function to include mmap in the
name, since it's only for MMAP buffers?
Best regards,
Tomasz
