On Tue, Nov 18, 2014 at 9:51 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> By default dma_map_sg syncs the mapped buffer to the device. But
> buf_prepare expects a buffer syncs for the cpu and the buffer
> will be synced to the device in the prepare memop.
>
> The reverse is true for dma_unmap_sg, buf_finish and the finish
> memop.
>
> To prevent unnecessary syncs we ask dma_(un)map_sg to skip the
> sync.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Pawel Osciak <pawel@xxxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-dma-contig.c | 24 +++++++++++++++----
> drivers/media/v4l2-core/videobuf2-dma-sg.c | 33 +++++++++++++++++++++-----
> 2 files changed, 47 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> index 0bfc488..b481d20 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
> @@ -511,7 +511,15 @@ static void vb2_dc_put_userptr(void *buf_priv)
> struct sg_table *sgt = buf->dma_sgt;
>
> if (sgt) {
> - dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
> + DEFINE_DMA_ATTRS(attrs);
> +
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
> + /*
> + * No need to sync to CPU, it's already synced to the CPU
> + * since the finish() memop will have been called before this.
> + */
> + dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> + buf->dma_dir, &attrs);
> if (!vma_is_io(buf->vma))
> vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
>
> @@ -568,6 +576,9 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
> struct sg_table *sgt;
> unsigned long contig_size;
> unsigned long dma_align = dma_get_cache_alignment();
> + DEFINE_DMA_ATTRS(attrs);
> +
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
>
> /* Only cache aligned DMA transfers are reliable */
> if (!IS_ALIGNED(vaddr | size, dma_align)) {
> @@ -654,8 +665,12 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
> kfree(pages);
> pages = NULL;
>
> - sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
> - buf->dma_dir);
> + /*
> + * No need to sync to the device, this will happen later when the
> + * prepare() memop is called.
> + */
> + sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> + buf->dma_dir, &attrs);
> if (sgt->nents <= 0) {
> pr_err("failed to map scatterlist\n");
> ret = -EIO;
> @@ -677,7 +692,8 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
> return buf;
>
> fail_map_sg:
> - dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
> + dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
> + buf->dma_dir, &attrs);
>
> fail_sgt_init:
> if (!vma_is_io(buf->vma))
> diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> index c2ec2c4..d75fcf1 100644
> --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
> +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
> @@ -107,6 +107,9 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size,
> struct sg_table *sgt;
> int ret;
> int num_pages;
> + DEFINE_DMA_ATTRS(attrs);
> +
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
>
> if (WARN_ON(alloc_ctx == NULL))
> return NULL;
> @@ -140,9 +143,13 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size,
> buf->dev = get_device(conf->dev);
>
> sgt = &buf->sg_table;
> - if (dma_map_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir) == 0)
> + /*
> + * No need to sync to the device, this will happen later when the
> + * prepare() memop is called.
> + */
> + if (dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->nents,
> + buf->dma_dir, &attrs) == 0)
> goto fail_map;
> - dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
>
> buf->handler.refcount = &buf->refcount;
> buf->handler.put = vb2_dma_sg_put;
> @@ -175,9 +182,13 @@ static void vb2_dma_sg_put(void *buf_priv)
> int i = buf->num_pages;
>
> if (atomic_dec_and_test(&buf->refcount)) {
> + DEFINE_DMA_ATTRS(attrs);
> +
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
> dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
> buf->num_pages);
> - dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> + dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->nents,
> + buf->dma_dir, &attrs);
> if (buf->vaddr)
> vm_unmap_ram(buf->vaddr, buf->num_pages);
> sg_free_table(buf->dma_sgt);
> @@ -227,6 +238,9 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
> int num_pages_from_user;
> struct vm_area_struct *vma;
> struct sg_table *sgt;
> + DEFINE_DMA_ATTRS(attrs);
> +
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
>
> buf = kzalloc(sizeof *buf, GFP_KERNEL);
> if (!buf)
> @@ -294,9 +308,13 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
> goto userptr_fail_alloc_table_from_pages;
>
> sgt = &buf->sg_table;
> - if (dma_map_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir) == 0)
> + /*
> + * No need to sync to the device, this will happen later when the
> + * prepare() memop is called.
> + */
> + if (dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->nents,
> + buf->dma_dir, &attrs) == 0)
> goto userptr_fail_map;
> - dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> return buf;
>
> userptr_fail_map:
> @@ -325,10 +343,13 @@ static void vb2_dma_sg_put_userptr(void *buf_priv)
> struct vb2_dma_sg_buf *buf = buf_priv;
> struct sg_table *sgt = &buf->sg_table;
> int i = buf->num_pages;
> + DEFINE_DMA_ATTRS(attrs);
> +
> + dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
>
> dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
> __func__, buf->num_pages);
> - dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> + dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir, &attrs);
> if (buf->vaddr)
> vm_unmap_ram(buf->vaddr, buf->num_pages);
> sg_free_table(buf->dma_sgt);
> --
> 2.1.1
>
--
Best regards,
Pawel Osciak
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