[PATCHv7 03/15] v4l: vb2: add support for shared buffer (dma_buf)
Tomasz Stanislawski
t.stanislaws at samsung.com
Thu Jun 14 06:37:37 PDT 2012
From: Sumit Semwal <sumit.semwal at ti.com>
This patch adds support for DMABUF memory type in videobuf2. It calls relevant
APIs of dma_buf for v4l reqbuf / qbuf / dqbuf operations.
For this version, the support is for videobuf2 as a user of the shared buffer;
so the allocation of the buffer is done outside of V4L2. [A sample allocator of
dma-buf shared buffer is given at [1]]
[1]: Rob Clark's DRM:
https://github.com/robclark/kernel-omap4/commits/drmplane-dmabuf
Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
[original work in the PoC for buffer sharing]
Signed-off-by: Sumit Semwal <sumit.semwal at ti.com>
Signed-off-by: Sumit Semwal <sumit.semwal at linaro.org>
Acked-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
drivers/media/video/videobuf2-core.c | 196 +++++++++++++++++++++++++++++++++-
include/media/videobuf2-core.h | 27 +++++
2 files changed, 219 insertions(+), 4 deletions(-)
diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
index 9d4e9ed..f43cfa4 100644
--- a/drivers/media/video/videobuf2-core.c
+++ b/drivers/media/video/videobuf2-core.c
@@ -109,6 +109,36 @@ static void __vb2_buf_userptr_put(struct vb2_buffer *vb)
}
/**
+ * __vb2_plane_dmabuf_put() - release memory associated with
+ * a DMABUF shared plane
+ */
+static void __vb2_plane_dmabuf_put(struct vb2_queue *q, struct vb2_plane *p)
+{
+ if (!p->mem_priv)
+ return;
+
+ if (p->dbuf_mapped)
+ call_memop(q, unmap_dmabuf, p->mem_priv);
+
+ call_memop(q, detach_dmabuf, p->mem_priv);
+ dma_buf_put(p->dbuf);
+ memset(p, 0, sizeof *p);
+}
+
+/**
+ * __vb2_buf_dmabuf_put() - release memory associated with
+ * a DMABUF shared buffer
+ */
+static void __vb2_buf_dmabuf_put(struct vb2_buffer *vb)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ unsigned int plane;
+
+ for (plane = 0; plane < vb->num_planes; ++plane)
+ __vb2_plane_dmabuf_put(q, &vb->planes[plane]);
+}
+
+/**
* __setup_offsets() - setup unique offsets ("cookies") for every plane in
* every buffer on the queue
*/
@@ -230,6 +260,8 @@ static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)
/* Free MMAP buffers or release USERPTR buffers */
if (q->memory == V4L2_MEMORY_MMAP)
__vb2_buf_mem_free(vb);
+ else if (q->memory == V4L2_MEMORY_DMABUF)
+ __vb2_buf_dmabuf_put(vb);
else
__vb2_buf_userptr_put(vb);
}
@@ -352,6 +384,12 @@ static int __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
*/
memcpy(b->m.planes, vb->v4l2_planes,
b->length * sizeof(struct v4l2_plane));
+
+ if (q->memory == V4L2_MEMORY_DMABUF) {
+ unsigned int plane;
+ for (plane = 0; plane < vb->num_planes; ++plane)
+ b->m.planes[plane].m.fd = 0;
+ }
} else {
/*
* We use length and offset in v4l2_planes array even for
@@ -363,6 +401,8 @@ static int __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
b->m.offset = vb->v4l2_planes[0].m.mem_offset;
else if (q->memory == V4L2_MEMORY_USERPTR)
b->m.userptr = vb->v4l2_planes[0].m.userptr;
+ else if (q->memory == V4L2_MEMORY_DMABUF)
+ b->m.fd = 0;
}
/*
@@ -454,6 +494,20 @@ static int __verify_mmap_ops(struct vb2_queue *q)
}
/**
+ * __verify_dmabuf_ops() - verify that all memory operations required for
+ * DMABUF queue type have been provided
+ */
+static int __verify_dmabuf_ops(struct vb2_queue *q)
+{
+ if (!(q->io_modes & VB2_DMABUF) || !q->mem_ops->attach_dmabuf ||
+ !q->mem_ops->detach_dmabuf || !q->mem_ops->map_dmabuf ||
+ !q->mem_ops->unmap_dmabuf)
+ return -EINVAL;
+
+ return 0;
+}
+
+/**
* vb2_reqbufs() - Initiate streaming
* @q: videobuf2 queue
* @req: struct passed from userspace to vidioc_reqbufs handler in driver
@@ -486,8 +540,9 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
return -EBUSY;
}
- if (req->memory != V4L2_MEMORY_MMAP
- && req->memory != V4L2_MEMORY_USERPTR) {
+ if (req->memory != V4L2_MEMORY_MMAP &&
+ req->memory != V4L2_MEMORY_DMABUF &&
+ req->memory != V4L2_MEMORY_USERPTR) {
dprintk(1, "reqbufs: unsupported memory type\n");
return -EINVAL;
}
@@ -516,6 +571,11 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
return -EINVAL;
}
+ if (req->memory == V4L2_MEMORY_DMABUF && __verify_dmabuf_ops(q)) {
+ dprintk(1, "reqbufs: DMABUF for current setup unsupported\n");
+ return -EINVAL;
+ }
+
if (req->count == 0 || q->num_buffers != 0 || q->memory != req->memory) {
/*
* We already have buffers allocated, so first check if they
@@ -622,8 +682,9 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
return -EBUSY;
}
- if (create->memory != V4L2_MEMORY_MMAP
- && create->memory != V4L2_MEMORY_USERPTR) {
+ if (create->memory != V4L2_MEMORY_MMAP &&
+ create->memory != V4L2_MEMORY_USERPTR &&
+ create->memory != V4L2_MEMORY_DMABUF) {
dprintk(1, "%s(): unsupported memory type\n", __func__);
return -EINVAL;
}
@@ -647,6 +708,11 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
return -EINVAL;
}
+ if (create->memory == V4L2_MEMORY_DMABUF && __verify_dmabuf_ops(q)) {
+ dprintk(1, "%s(): DMABUF for current setup unsupported\n", __func__);
+ return -EINVAL;
+ }
+
if (q->num_buffers == VIDEO_MAX_FRAME) {
dprintk(1, "%s(): maximum number of buffers already allocated\n",
__func__);
@@ -842,6 +908,14 @@ static int __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b,
b->m.planes[plane].length;
}
}
+ if (b->memory == V4L2_MEMORY_DMABUF) {
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ v4l2_planes[plane].bytesused =
+ b->m.planes[plane].bytesused;
+ v4l2_planes[plane].m.fd =
+ b->m.planes[plane].m.fd;
+ }
+ }
} else {
/*
* Single-planar buffers do not use planes array,
@@ -856,6 +930,10 @@ static int __fill_vb2_buffer(struct vb2_buffer *vb, const struct v4l2_buffer *b,
v4l2_planes[0].m.userptr = b->m.userptr;
v4l2_planes[0].length = b->length;
}
+
+ if (b->memory == V4L2_MEMORY_DMABUF)
+ v4l2_planes[0].m.fd = b->m.fd;
+
}
vb->v4l2_buf.field = b->field;
@@ -960,6 +1038,100 @@ static int __qbuf_mmap(struct vb2_buffer *vb, const struct v4l2_buffer *b)
}
/**
+ * __qbuf_dmabuf() - handle qbuf of a DMABUF buffer
+ */
+static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b)
+{
+ struct v4l2_plane planes[VIDEO_MAX_PLANES];
+ struct vb2_queue *q = vb->vb2_queue;
+ void *mem_priv;
+ unsigned int plane;
+ int ret;
+ int write = !V4L2_TYPE_IS_OUTPUT(q->type);
+
+ /* Verify and copy relevant information provided by the userspace */
+ ret = __fill_vb2_buffer(vb, b, planes);
+ if (ret)
+ return ret;
+
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ struct dma_buf *dbuf = dma_buf_get(planes[plane].m.fd);
+
+ if (IS_ERR_OR_NULL(dbuf)) {
+ dprintk(1, "qbuf: invalid dmabuf fd for "
+ "plane %d\n", plane);
+ ret = -EINVAL;
+ goto err;
+ }
+
+ /* Skip the plane if already verified */
+ if (dbuf == vb->planes[plane].dbuf) {
+ planes[plane].length = dbuf->size;
+ dma_buf_put(dbuf);
+ continue;
+ }
+
+ dprintk(3, "qbuf: buffer description for plane %d changed, "
+ "reattaching dma buf\n", plane);
+
+ /* Release previously acquired memory if present */
+ __vb2_plane_dmabuf_put(q, &vb->planes[plane]);
+
+ /* Acquire each plane's memory */
+ mem_priv = call_memop(q, attach_dmabuf, q->alloc_ctx[plane],
+ dbuf, q->plane_sizes[plane], write);
+ if (IS_ERR(mem_priv)) {
+ dprintk(1, "qbuf: failed acquiring dmabuf "
+ "memory for plane %d\n", plane);
+ ret = PTR_ERR(mem_priv);
+ goto err;
+ }
+
+ planes[plane].length = dbuf->size;
+ vb->planes[plane].dbuf = dbuf;
+ vb->planes[plane].mem_priv = mem_priv;
+ }
+
+ /* TODO: This pins the buffer(s) with dma_buf_map_attachment()).. but
+ * really we want to do this just before the DMA, not while queueing
+ * the buffer(s)..
+ */
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ ret = call_memop(q, map_dmabuf, vb->planes[plane].mem_priv);
+ if (ret) {
+ dprintk(1, "qbuf: failed mapping dmabuf "
+ "memory for plane %d\n", plane);
+ goto err;
+ }
+ vb->planes[plane].dbuf_mapped = 1;
+ }
+
+ /*
+ * Call driver-specific initialization on the newly acquired buffer,
+ * if provided.
+ */
+ ret = call_qop(q, buf_init, vb);
+ if (ret) {
+ dprintk(1, "qbuf: buffer initialization failed\n");
+ goto err;
+ }
+
+ /*
+ * Now that everything is in order, copy relevant information
+ * provided by userspace.
+ */
+ for (plane = 0; plane < vb->num_planes; ++plane)
+ vb->v4l2_planes[plane] = planes[plane];
+
+ return 0;
+err:
+ /* In case of errors, release planes that were already acquired */
+ __vb2_buf_dmabuf_put(vb);
+
+ return ret;
+}
+
+/**
* __enqueue_in_driver() - enqueue a vb2_buffer in driver for processing
*/
static void __enqueue_in_driver(struct vb2_buffer *vb)
@@ -983,6 +1155,9 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
case V4L2_MEMORY_USERPTR:
ret = __qbuf_userptr(vb, b);
break;
+ case V4L2_MEMORY_DMABUF:
+ ret = __qbuf_dmabuf(vb, b);
+ break;
default:
WARN(1, "Invalid queue type\n");
ret = -EINVAL;
@@ -1338,6 +1513,19 @@ int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking)
return ret;
}
+ /* TODO: this unpins the buffer(dma_buf_unmap_attachment()).. but
+ * really we want to do this just after DMA, not when the
+ * buffer is dequeued..
+ */
+ if (q->memory == V4L2_MEMORY_DMABUF) {
+ unsigned int i;
+
+ for (i = 0; i < vb->num_planes; ++i) {
+ call_memop(q, unmap_dmabuf, vb->planes[i].mem_priv);
+ vb->planes[i].dbuf_mapped = 0;
+ }
+ }
+
switch (vb->state) {
case VB2_BUF_STATE_DONE:
dprintk(3, "dqbuf: Returning done buffer\n");
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index a15d1f1..859bbaf 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -16,6 +16,7 @@
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/videodev2.h>
+#include <linux/dma-buf.h>
struct vb2_alloc_ctx;
struct vb2_fileio_data;
@@ -41,6 +42,20 @@ struct vb2_fileio_data;
* argument to other ops in this structure
* @put_userptr: inform the allocator that a USERPTR buffer will no longer
* be used
+ * @attach_dmabuf: attach a shared struct dma_buf for a hardware operation;
+ * used for DMABUF memory types; alloc_ctx is the alloc context
+ * dbuf is the shared dma_buf; returns NULL on failure;
+ * allocator private per-buffer structure on success;
+ * this needs to be used for further accesses to the buffer
+ * @detach_dmabuf: inform the exporter of the buffer that the current DMABUF
+ * buffer is no longer used; the buf_priv argument is the
+ * allocator private per-buffer structure previously returned
+ * from the attach_dmabuf callback
+ * @map_dmabuf: request for access to the dmabuf from allocator; the allocator
+ * of dmabuf is informed that this driver is going to use the
+ * dmabuf
+ * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified
+ * that this driver is done using the dmabuf for now
* @vaddr: return a kernel virtual address to a given memory buffer
* associated with the passed private structure or NULL if no
* such mapping exists
@@ -56,6 +71,8 @@ struct vb2_fileio_data;
* Required ops for USERPTR types: get_userptr, put_userptr.
* Required ops for MMAP types: alloc, put, num_users, mmap.
* Required ops for read/write access types: alloc, put, num_users, vaddr
+ * Required ops for DMABUF types: attach_dmabuf, detach_dmabuf, map_dmabuf,
+ * unmap_dmabuf.
*/
struct vb2_mem_ops {
void *(*alloc)(void *alloc_ctx, unsigned long size);
@@ -65,6 +82,12 @@ struct vb2_mem_ops {
unsigned long size, int write);
void (*put_userptr)(void *buf_priv);
+ void *(*attach_dmabuf)(void *alloc_ctx, struct dma_buf *dbuf,
+ unsigned long size, int write);
+ void (*detach_dmabuf)(void *buf_priv);
+ int (*map_dmabuf)(void *buf_priv);
+ void (*unmap_dmabuf)(void *buf_priv);
+
void *(*vaddr)(void *buf_priv);
void *(*cookie)(void *buf_priv);
@@ -75,6 +98,8 @@ struct vb2_mem_ops {
struct vb2_plane {
void *mem_priv;
+ struct dma_buf *dbuf;
+ unsigned int dbuf_mapped;
};
/**
@@ -83,12 +108,14 @@ struct vb2_plane {
* @VB2_USERPTR: driver supports USERPTR with streaming API
* @VB2_READ: driver supports read() style access
* @VB2_WRITE: driver supports write() style access
+ * @VB2_DMABUF: driver supports DMABUF with streaming API
*/
enum vb2_io_modes {
VB2_MMAP = (1 << 0),
VB2_USERPTR = (1 << 1),
VB2_READ = (1 << 2),
VB2_WRITE = (1 << 3),
+ VB2_DMABUF = (1 << 4),
};
/**
--
1.7.9.5
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