[PATCH 0/3] Integration of vb2-vmalloc and VIVI with dmabuf

[PATCH 0/3] Integration of vb2-vmalloc and VIVI with dmabuf

[Tomasz Stanislawski]

Hello everyone,
The patcheset adds support for DMABUF [1] importing to vmalloc allocator in
videobuf2 stack. This is an incremental patch to 'Integration of videobuf2
with dmabuf' patchset [2]. This patch makes use of vmap extension for dmabuf
proposed by Dave Airlie [3].

The vmap was preferred over the kmap extension. The reason is that VIVI driver
requires the memory to be mapped into a contiguous block of virtual memory
accessible by kernel.  The workaround could be mapping all pages into kernel
memory but the dmabuf-kmap interface does guarantee that consecutive pages are
mapped into consecutive addresses.

[1] https://lkml.org/lkml/2011/12/26/29
[2] http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/46586
[3] http://cgit.freedesktop.org/~airlied/linux/commit/?h=drm-dmabuf2&id=c481a5451744fe3c4c950a446be10d3212d633d8

Dave Airlie (1):
  dma-buf: add vmap interface

Tomasz Stanislawski (2):
  v4l: vb2-vmalloc: add support for dmabuf importing
  v4l: vivi: support for dmabuf importing

 drivers/base/dma-buf.c                  |   29 ++++++++++++++++
 drivers/media/video/Kconfig             |    1 +
 drivers/media/video/videobuf2-vmalloc.c |   56 +++++++++++++++++++++++++++++++
 drivers/media/video/vivi.c              |    2 +-
 include/linux/dma-buf.h                 |   16 +++++++++
 5 files changed, 103 insertions(+), 1 deletions(-)

-- 
1.7.5.4

[PATCH 1/3] dma-buf: add vmap interface

[Tomasz Stanislawski]

From: Dave Airlie <airlied@redhat.com>

Add vmap to dmabuf interface.

Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/base/dma-buf.c  |   29 +++++++++++++++++++++++++++++
 include/linux/dma-buf.h |   16 ++++++++++++++++
 2 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 07cbbc6..3068258 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -406,3 +406,32 @@ void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
 		dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
 }
 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
+
+/**
+ * dma_buf_vmap - Create virtual mapping for the buffer object into kernel address space. The same restrictions as for vmap and friends apply.
+ * @dma_buf:	[in]	buffer to vmap
+ *
+ * This call may fail due to lack of virtual mapping address space.
+ */
+void *dma_buf_vmap(struct dma_buf *dmabuf)
+{
+	WARN_ON(!dmabuf);
+
+	if (dmabuf->ops->vmap)
+		return dmabuf->ops->vmap(dmabuf);
+	return NULL;
+}
+EXPORT_SYMBOL(dma_buf_vmap);
+
+/**
+ * dma_buf_vunmap - Unmap a page obtained by dma_buf_vmap.
+ * @dma_buf:	[in]	buffer to vmap
+ */
+void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+{
+	WARN_ON(!dmabuf);
+
+	if (dmabuf->ops->vunmap)
+		dmabuf->ops->vunmap(dmabuf, vaddr);
+}
+EXPORT_SYMBOL(dma_buf_vunmap);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 3efbfc2..4a6b371 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -92,6 +92,9 @@ struct dma_buf_ops {
 	void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
 	void *(*kmap)(struct dma_buf *, unsigned long);
 	void (*kunmap)(struct dma_buf *, unsigned long, void *);
+
+	void *(*vmap)(struct dma_buf *);
+	void (*vunmap)(struct dma_buf *, void *vaddr);
 };
 
 /**
@@ -167,6 +170,9 @@ void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
 void *dma_buf_kmap(struct dma_buf *, unsigned long);
 void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
+
+void *dma_buf_vmap(struct dma_buf *);
+void dma_buf_vunmap(struct dma_buf *, void *vaddr);
 #else
 
 static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
@@ -248,6 +254,16 @@ static inline void dma_buf_kunmap(struct dma_buf *dmabuf,
 				  unsigned long pnum, void *vaddr)
 {
 }
+
+static inline void *dma_buf_vmap(struct dma_buf *dmabuf)
+{
+	return NULL;
+}
+
+static inline void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
+{
+}
+
 #endif /* CONFIG_DMA_SHARED_BUFFER */
 
 #endif /* __DMA_BUF_H__ */
-- 
1.7.5.4

[PATCH 2/3] v4l: vb2-vmalloc: add support for dmabuf importing

[Tomasz Stanislawski]

This patch adds support for importing DMABUF files for
vmalloc allocator in Videobuf2.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/media/video/videobuf2-vmalloc.c |   56 +++++++++++++++++++++++++++++++
 1 files changed, 56 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/videobuf2-vmalloc.c b/drivers/media/video/videobuf2-vmalloc.c
index 6b5ca6c..305032f 100644
--- a/drivers/media/video/videobuf2-vmalloc.c
+++ b/drivers/media/video/videobuf2-vmalloc.c
@@ -29,6 +29,7 @@ struct vb2_vmalloc_buf {
 	unsigned int			n_pages;
 	atomic_t			refcount;
 	struct vb2_vmarea_handler	handler;
+	struct dma_buf			*dbuf;
 };
 
 static void vb2_vmalloc_put(void *buf_priv);
@@ -206,11 +207,66 @@ static int vb2_vmalloc_mmap(void *buf_priv, struct vm_area_struct *vma)
 	return 0;
 }
 
+/*********************************************/
+/*       callbacks for DMABUF buffers        */
+/*********************************************/
+
+static int vb2_vmalloc_map_dmabuf(void *mem_priv)
+{
+	struct vb2_vmalloc_buf *buf = mem_priv;
+
+	buf->vaddr = dma_buf_vmap(buf->dbuf);
+
+	return buf->vaddr ? 0 : -EFAULT;
+}
+
+static void vb2_vmalloc_unmap_dmabuf(void *mem_priv)
+{
+	struct vb2_vmalloc_buf *buf = mem_priv;
+
+	dma_buf_vunmap(buf->dbuf, buf->vaddr);
+	buf->vaddr = NULL;
+}
+
+static void vb2_vmalloc_detach_dmabuf(void *mem_priv)
+{
+	struct vb2_vmalloc_buf *buf = mem_priv;
+
+	if (buf->vaddr)
+		dma_buf_vunmap(buf->dbuf, buf->vaddr);
+
+	kfree(buf);
+}
+
+static void *vb2_vmalloc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
+	unsigned long size, int write)
+{
+	struct vb2_vmalloc_buf *buf;
+
+	if (dbuf->size < size)
+		return ERR_PTR(-EFAULT);
+
+	buf = kzalloc(sizeof *buf, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	buf->dbuf = dbuf;
+	buf->write = write;
+	buf->size = size;
+
+	return buf;
+}
+
+
 const struct vb2_mem_ops vb2_vmalloc_memops = {
 	.alloc		= vb2_vmalloc_alloc,
 	.put		= vb2_vmalloc_put,
 	.get_userptr	= vb2_vmalloc_get_userptr,
 	.put_userptr	= vb2_vmalloc_put_userptr,
+	.map_dmabuf	= vb2_vmalloc_map_dmabuf,
+	.unmap_dmabuf	= vb2_vmalloc_unmap_dmabuf,
+	.attach_dmabuf	= vb2_vmalloc_attach_dmabuf,
+	.detach_dmabuf	= vb2_vmalloc_detach_dmabuf,
 	.vaddr		= vb2_vmalloc_vaddr,
 	.mmap		= vb2_vmalloc_mmap,
 	.num_users	= vb2_vmalloc_num_users,
-- 
1.7.5.4

[PATCH 3/3] v4l: vivi: support for dmabuf importing

[Tomasz Stanislawski]

This patch enhances VIVI driver with a support for importing a buffer
from DMABUF file descriptors.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 drivers/media/video/Kconfig |    1 +
 drivers/media/video/vivi.c  |    2 +-
 2 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index f2479c5..d6294d6 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -625,6 +625,7 @@ config VIDEO_VIVI
 	depends on FRAMEBUFFER_CONSOLE || STI_CONSOLE
 	select FONT_8x16
 	select VIDEOBUF2_VMALLOC
+	select DMA_SHARED_BUFFER
 	default n
 	---help---
 	  Enables a virtual video driver. This device shows a color bar
diff --git a/drivers/media/video/vivi.c b/drivers/media/video/vivi.c
index 5e8b071..489d685 100644
--- a/drivers/media/video/vivi.c
+++ b/drivers/media/video/vivi.c
@@ -1289,7 +1289,7 @@ static int __init vivi_create_instance(int inst)
 	q = &dev->vb_vidq;
 	memset(q, 0, sizeof(dev->vb_vidq));
 	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
-	q->io_modes = VB2_MMAP | VB2_USERPTR | VB2_READ;
+	q->io_modes = VB2_MMAP | VB2_USERPTR | VB2_DMABUF | VB2_READ;
 	q->drv_priv = dev;
 	q->buf_struct_size = sizeof(struct vivi_buffer);
 	q->ops = &vivi_video_qops;
-- 
1.7.5.4

Re: [PATCH 1/3] dma-buf: add vmap interface

[Sylwester Nawrocki]

Hi,

On 04/10/2012 12:11 PM, Tomasz Stanislawski wrote:
> From: Dave Airlie<airlied@redhat.com>
>
> Add vmap to dmabuf interface.
>
> Signed-off-by: Dave Airlie<airlied@redhat.com>
> ---
>   drivers/base/dma-buf.c  |   29 +++++++++++++++++++++++++++++
>   include/linux/dma-buf.h |   16 ++++++++++++++++
>   2 files changed, 45 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index 07cbbc6..3068258 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -406,3 +406,32 @@ void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
>   		dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
>   }
>   EXPORT_SYMBOL_GPL(dma_buf_kunmap);
> +
> +/**
> + * dma_buf_vmap - Create virtual mapping for the buffer object into kernel address space. The same restrictions as for vmap and friends apply.
> + * @dma_buf:	[in]	buffer to vmap
> + *
> + * This call may fail due to lack of virtual mapping address space.
> + */
> +void *dma_buf_vmap(struct dma_buf *dmabuf)
> +{
> +	WARN_ON(!dmabuf);

How about replacing this with:

	if (WARN_ON(!dmabuf))
		return NULL;

to avoid null pointer dereference right below ?

> +	if (dmabuf->ops->vmap)
> +		return dmabuf->ops->vmap(dmabuf);
> +	return NULL;
> +}
> +EXPORT_SYMBOL(dma_buf_vmap);
> +
> +/**
> + * dma_buf_vunmap - Unmap a page obtained by dma_buf_vmap.
> + * @dma_buf:	[in]	buffer to vmap
> + */
> +void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
> +{
> +	WARN_ON(!dmabuf);

and here
	if (WARN_ON(!dmabuf))
		return;
?
> +	if (dmabuf->ops->vunmap)
> +		dmabuf->ops->vunmap(dmabuf, vaddr);
> +}
> +EXPORT_SYMBOL(dma_buf_vunmap);

--

Regards,
Sylwester