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

Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> · Mon, 01 Feb 2016 14:29:25 +0100

Hello,

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

Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

---
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

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