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linux-sg2042
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[media] vb2: use dma_map_sg_attrs to prevent unnecessary sync 

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@cisco.com>
Acked-by: Pawel Osciak <pawel@osciak.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Hans Verkuil 2014-11-18 09:51:08 -03:00 committed by Mauro Carvalho Chehab
parent f5294f455a
commit 251a79f8f5
2 changed files with 47 additions and 10 deletions
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24
drivers/media/v4l2-core/videobuf2-dma-contig.c
View File

@ -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))

33
drivers/media/v4l2-core/videobuf2-dma-sg.c
View File

@ -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);
@ -228,6 +239,9 @@ 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)
@ -296,9 +310,13 @@ 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:
@ -327,10 +345,13 @@ 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);