Linaro-mm-sig January 2017

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[PATCH] allow buffers allocation with DMABUF memory type

by Benjamin Gaignard

Until now the only way to make the driver allocate buffers and share them using dma_buf was to use V4L2_MEMORY_MMAP memory type. Use of MMAP memory type is a problem because vb2 never call dma_buf_map_attachment() to attach itself while queuing the buffer so dma_buf importer will not know that another device use this buffer. This patch allow to allocate buffer even for DMABUF memory type and correctly manage dma_buf buffer attachment. vb2_mem_ops attach_dmabuf() prototype has been changed to be able to distinguish if the attachment is done on a already existing buffer or on imported one. Signed-off-by: Benjamin Gaignard <benjamin.gaignard(a)linaro.org> --- drivers/media/v4l2-core/videobuf2-core.c | 76 ++++++++++++++++++++++++-- drivers/media/v4l2-core/videobuf2-dma-contig.c | 10 ++-- drivers/media/v4l2-core/videobuf2-dma-sg.c | 8 ++- drivers/media/v4l2-core/videobuf2-vmalloc.c | 8 ++- include/media/videobuf2-core.h | 5 +- 5 files changed, 91 insertions(+), 16 deletions(-) diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 1329dcc..c5968aa 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -337,6 +337,67 @@ static void __setup_offsets(struct vb2_queue *q, unsigned int n) } /** + * __setup_dmabufs() - setup dmabuf fd for every plane in + * every buffer on the queue + */ +static void __setup_dmabufs(struct vb2_queue *q, unsigned int n) +{ + unsigned int buffer, plane; + struct vb2_buffer *vb; + struct vb2_plane *vb_plane; + struct dma_buf *dbuf; + void *mem_priv; + int fd; + int write = !V4L2_TYPE_IS_OUTPUT(q->type); + int flags = write ? O_WRONLY : O_RDONLY; + + for (buffer = q->num_buffers; buffer < q->num_buffers + n; ++buffer) { + vb = q->bufs[buffer]; + if (!vb) + continue; + + for (plane = 0; plane < vb->num_planes; ++plane) { + vb_plane = &vb->planes[plane]; + + dbuf = call_ptr_memop(vb, get_dmabuf, + vb_plane->mem_priv, + flags & O_ACCMODE); + if (IS_ERR_OR_NULL(dbuf)) { + dprintk(1, "Failed to export buffer %d, " \ + "plane %d\n", buffer, plane); + continue; + } + + fd = dma_buf_fd(dbuf, flags & ~O_ACCMODE); + if (fd < 0) { + dprintk(3, "buffer %d, plane %d failed " \ + "to export (%d)\n", buffer, plane, fd); + dma_buf_put(dbuf); + continue; + } + + /* Acquire each plane's memory */ + mem_priv = call_ptr_memop(vb, attach_dmabuf, + q->alloc_ctx[plane], dbuf, + vb->v4l2_planes[plane].length, + write, vb_plane->mem_priv); + if (IS_ERR(mem_priv)) { + dprintk(1, "Buffer %d plane %d failed "\ + "to attach dmabuf\n", buffer, plane); + dma_buf_put(dbuf); + continue; + } + + vb_plane->dbuf = dbuf; + vb->v4l2_planes[plane].m.fd = fd; + + dprintk(3, "Buffer %d, plane %d fd %x\n", + buffer, plane, fd); + } + } +} + +/** * __vb2_queue_alloc() - allocate videobuf buffer structures and (for MMAP type) * video buffer memory for all buffers/planes on the queue and initializes the * queue @@ -369,8 +430,9 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum v4l2_memory memory, vb->v4l2_buf.type = q->type; vb->v4l2_buf.memory = memory; - /* Allocate video buffer memory for the MMAP type */ - if (memory == V4L2_MEMORY_MMAP) { + /* Allocate video buffer memory for the MMAP and DMABUF types */ + if (memory == V4L2_MEMORY_MMAP || + memory == V4L2_MEMORY_DMABUF) { ret = __vb2_buf_mem_alloc(vb); if (ret) { dprintk(1, "failed allocating memory for " @@ -400,6 +462,9 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum v4l2_memory memory, if (memory == V4L2_MEMORY_MMAP) __setup_offsets(q, buffer); + if (memory == V4L2_MEMORY_DMABUF) + __setup_dmabufs(q, buffer); + dprintk(1, "allocated %d buffers, %d plane(s) each\n", buffer, num_planes); @@ -859,7 +924,7 @@ static int __verify_memory_type(struct vb2_queue *q, * to be used during streaming, * 4) allocates internal buffer structures (struct vb2_buffer), according to * the agreed parameters, - * 5) for MMAP memory type, allocates actual video memory, using the + * 5) for MMAP and DMABUF memory types, allocates actual video memory, using the * memory handling/allocation routines provided during queue initialization * * If req->count is 0, all the memory will be freed instead. @@ -885,7 +950,8 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req) * are not in use and can be freed. */ mutex_lock(&q->mmap_lock); - if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) { + if ((q->memory == V4L2_MEMORY_MMAP || + q->memory == V4L2_MEMORY_DMABUF) && __buffers_in_use(q)) { mutex_unlock(&q->mmap_lock); dprintk(1, "memory in use, cannot free\n"); return -EBUSY; @@ -1540,7 +1606,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const struct v4l2_buffer *b) /* Acquire each plane's memory */ mem_priv = call_ptr_memop(vb, attach_dmabuf, q->alloc_ctx[plane], - dbuf, planes[plane].length, dma_dir); + dbuf, planes[plane].length, dma_dir, NULL); if (IS_ERR(mem_priv)) { dprintk(1, "failed to attach dmabuf\n"); ret = PTR_ERR(mem_priv); diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c index b481d20..8dc945e 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c @@ -793,7 +793,7 @@ static void vb2_dc_detach_dmabuf(void *mem_priv) struct vb2_dc_buf *buf = mem_priv; /* if vb2 works correctly you should never detach mapped buffer */ - if (WARN_ON(buf->dma_addr)) + if (WARN_ON(buf->dma_sgt)) vb2_dc_unmap_dmabuf(buf); /* detach this attachment */ @@ -802,16 +802,18 @@ static void vb2_dc_detach_dmabuf(void *mem_priv) } static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf, - unsigned long size, enum dma_data_direction dma_dir) + unsigned long size, enum dma_data_direction dma_dir, void *buf_priv) { struct vb2_dc_conf *conf = alloc_ctx; - struct vb2_dc_buf *buf; + struct vb2_dc_buf *buf = buf_priv; struct dma_buf_attachment *dba; if (dbuf->size < size) return ERR_PTR(-EFAULT); - buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) return ERR_PTR(-ENOMEM); diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c index b1838ab..b9855fd 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-sg.c +++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c @@ -667,16 +667,18 @@ static void vb2_dma_sg_detach_dmabuf(void *mem_priv) } static void *vb2_dma_sg_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf, - unsigned long size, enum dma_data_direction dma_dir) + unsigned long size, enum dma_data_direction dma_dir, void *buf_priv) { struct vb2_dma_sg_conf *conf = alloc_ctx; - struct vb2_dma_sg_buf *buf; + struct vb2_dma_sg_buf *buf = buf_priv; struct dma_buf_attachment *dba; if (dbuf->size < size) return ERR_PTR(-EFAULT); - buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) return ERR_PTR(-ENOMEM); diff --git a/drivers/media/v4l2-core/videobuf2-vmalloc.c b/drivers/media/v4l2-core/videobuf2-vmalloc.c index bcde885..373294c 100644 --- a/drivers/media/v4l2-core/videobuf2-vmalloc.c +++ b/drivers/media/v4l2-core/videobuf2-vmalloc.c @@ -416,14 +416,16 @@ static void vb2_vmalloc_detach_dmabuf(void *mem_priv) } static void *vb2_vmalloc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf, - unsigned long size, enum dma_data_direction dma_dir) + unsigned long size, enum dma_data_direction dma_dir, void *buf_priv) { - struct vb2_vmalloc_buf *buf; + struct vb2_vmalloc_buf *buf = buf_priv; if (dbuf->size < size) return ERR_PTR(-EFAULT); - buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) return ERR_PTR(-ENOMEM); diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index a5790fd..374b26b 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -49,6 +49,8 @@ struct vb2_threadio_data; * 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; + * if private per-buffer structure is provided reuse it + * instead of allocating a new one. * 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 @@ -98,7 +100,8 @@ struct vb2_mem_ops { void *(*attach_dmabuf)(void *alloc_ctx, struct dma_buf *dbuf, unsigned long size, - enum dma_data_direction dma_dir); + enum dma_data_direction dma_dir, + void *buf_priv); void (*detach_dmabuf)(void *buf_priv); int (*map_dmabuf)(void *buf_priv); void (*unmap_dmabuf)(void *buf_priv); -- 1.9.1

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Linaro-mm-sig January 2017