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

Marek Szyprowski Mon, 01 Feb 2016 05:30:08 -0800

Hello,

On 2016-01-11 18:30, Douglas Anderson wrote:

From: Tomasz Figa <[email protected]>


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 <[email protected]>
Signed-off-by: Douglas Anderson <[email protected]>


Acked-by: Marek Szyprowski <[email protected]>

---
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;


Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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

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