[PATCH v6 4/5] videobuf2-dc: Let drivers specify DMA attrs

From: Douglas Anderson
Date: Mon Jan 11 2016 - 12:33:04 EST


From: Tomasz Figa <tfiga@xxxxxxxxxxxx>

DMA allocations might be subject to certain reqiurements specific to the
hardware using the buffers, such as availability of kernel mapping (for
contents fix-ups in the driver). The only entity that knows them is the
driver, so it must share this knowledge with vb2-dc.

This patch extends the alloc_ctx initialization interface to let the
driver specify DMA attrs, which are then stored inside the allocation
context and will be used for all allocations with that context.

As a side effect, all dma_*_coherent() calls are turned into
dma_*_attrs() calls, because the attributes need to be carried over
through all DMA operations.

Signed-off-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
Changes in v6: None
Changes in v5:
- Let drivers specify DMA attrs new for v5

Changes in v4: None
Changes in v3: None
Changes in v2: None

drivers/media/v4l2-core/videobuf2-dma-contig.c | 33 +++++++++++++++++---------
include/media/videobuf2-dma-contig.h | 11 ++++++++-
2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index c33127284cfe..5361197f3e57 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -23,13 +23,16 @@

struct vb2_dc_conf {
struct device *dev;
+ struct dma_attrs attrs;
};

struct vb2_dc_buf {
struct device *dev;
void *vaddr;
unsigned long size;
+ void *cookie;
dma_addr_t dma_addr;
+ struct dma_attrs attrs;
enum dma_data_direction dma_dir;
struct sg_table *dma_sgt;
struct frame_vector *vec;
@@ -131,7 +134,8 @@ static void vb2_dc_put(void *buf_priv)
sg_free_table(buf->sgt_base);
kfree(buf->sgt_base);
}
- dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
+ dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
+ &buf->attrs);
put_device(buf->dev);
kfree(buf);
}
@@ -147,14 +151,18 @@ static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size,
if (!buf)
return ERR_PTR(-ENOMEM);

- buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
- GFP_KERNEL | gfp_flags);
- if (!buf->vaddr) {
+ buf->attrs = conf->attrs;
+ buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
+ GFP_KERNEL | gfp_flags, &buf->attrs);
+ if (!buf->cookie) {
dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
kfree(buf);
return ERR_PTR(-ENOMEM);
}

+ if (!dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, &buf->attrs))
+ buf->vaddr = buf->cookie;
+
/* Prevent the device from being released while the buffer is used */
buf->dev = get_device(dev);
buf->size = size;
@@ -185,8 +193,8 @@ static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
*/
vma->vm_pgoff = 0;

- ret = dma_mmap_coherent(buf->dev, vma, buf->vaddr,
- buf->dma_addr, buf->size);
+ ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
+ buf->dma_addr, buf->size, &buf->attrs);

if (ret) {
pr_err("Remapping memory failed, error: %d\n", ret);
@@ -329,7 +337,7 @@ static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
{
struct vb2_dc_buf *buf = dbuf->priv;

- return buf->vaddr + pgnum * PAGE_SIZE;
+ return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
}

static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
@@ -368,8 +376,8 @@ static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
return NULL;
}

- ret = dma_get_sgtable(buf->dev, sgt, buf->vaddr, buf->dma_addr,
- buf->size);
+ ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
+ buf->size, &buf->attrs);
if (ret < 0) {
dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
kfree(sgt);
@@ -721,7 +729,8 @@ const struct vb2_mem_ops vb2_dma_contig_memops = {
};
EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);

-void *vb2_dma_contig_init_ctx(struct device *dev)
+void *vb2_dma_contig_init_ctx_attrs(struct device *dev,
+ struct dma_attrs *attrs)
{
struct vb2_dc_conf *conf;

@@ -730,10 +739,12 @@ void *vb2_dma_contig_init_ctx(struct device *dev)
return ERR_PTR(-ENOMEM);

conf->dev = dev;
+ if (attrs)
+ conf->attrs = *attrs;

return conf;
}
-EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
+EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx_attrs);

void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
{
diff --git a/include/media/videobuf2-dma-contig.h b/include/media/videobuf2-dma-contig.h
index c33dfa69d7ab..2087c9a68be3 100644
--- a/include/media/videobuf2-dma-contig.h
+++ b/include/media/videobuf2-dma-contig.h
@@ -16,6 +16,8 @@
#include <media/videobuf2-v4l2.h>
#include <linux/dma-mapping.h>

+struct dma_attrs;
+
static inline dma_addr_t
vb2_dma_contig_plane_dma_addr(struct vb2_buffer *vb, unsigned int plane_no)
{
@@ -24,7 +26,14 @@ vb2_dma_contig_plane_dma_addr(struct vb2_buffer *vb, unsigned int plane_no)
return *addr;
}

-void *vb2_dma_contig_init_ctx(struct device *dev);
+void *vb2_dma_contig_init_ctx_attrs(struct device *dev,
+ struct dma_attrs *attrs);
+
+static inline void *vb2_dma_contig_init_ctx(struct device *dev)
+{
+ return vb2_dma_contig_init_ctx_attrs(dev, NULL);
+}
+
void vb2_dma_contig_cleanup_ctx(void *alloc_ctx);

extern const struct vb2_mem_ops vb2_dma_contig_memops;
--
2.6.0.rc2.230.g3dd15c0