diff options
Diffstat (limited to 'include/media/videobuf2-core.h')
| -rw-r--r-- | include/media/videobuf2-core.h | 217 |
1 files changed, 154 insertions, 63 deletions
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index bbb3f26fbde9..9b02aeba4108 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -18,6 +18,7 @@ #include <linux/dma-buf.h> #include <linux/bitops.h> #include <media/media-request.h> +#include <media/frame_vector.h> #define VB2_MAX_FRAME (32) #define VB2_MAX_PLANES (8) @@ -45,6 +46,7 @@ enum vb2_memory { struct vb2_fileio_data; struct vb2_threadio_data; +struct vb2_buffer; /** * struct vb2_mem_ops - memory handling/memory allocator operations. @@ -52,10 +54,8 @@ struct vb2_threadio_data; * return ERR_PTR() on failure or a pointer to allocator private, * per-buffer data on success; the returned private structure * will then be passed as @buf_priv argument to other ops in this - * structure. Additional gfp_flags to use when allocating the - * are also passed to this operation. These flags are from the - * gfp_flags field of vb2_queue. The size argument to this function - * shall be *page aligned*. + * structure. The size argument to this function shall be + * *page aligned*. * @put: inform the allocator that the buffer will no longer be used; * usually will result in the allocator freeing the buffer (if * no other users of this buffer are present); the @buf_priv @@ -65,13 +65,17 @@ struct vb2_threadio_data; * DMABUF memory types. * @get_userptr: acquire userspace memory for a hardware operation; used for * USERPTR memory types; vaddr is the address passed to the - * videobuf layer when queuing a video buffer of USERPTR type; + * videobuf2 layer when queuing a video buffer of USERPTR type; * should return an allocator private per-buffer structure * associated with the buffer on success, ERR_PTR() on failure; * the returned private structure will then be passed as @buf_priv * argument to other ops in this structure. * @put_userptr: inform the allocator that a USERPTR buffer will no longer * be used. + * @prepare: called every time the buffer is passed from userspace to the + * driver, useful for cache synchronisation, optional. + * @finish: called every time the buffer is passed back from the driver + * to the userspace, also optional. * @attach_dmabuf: attach a shared &struct dma_buf for a hardware operation; * used for DMABUF memory types; dev is the alloc device * dbuf is the shared dma_buf; returns ERR_PTR() on failure; @@ -86,10 +90,6 @@ struct vb2_threadio_data; * dmabuf. * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified * that this driver is done using the dmabuf for now. - * @prepare: called every time the buffer is passed from userspace to the - * driver, useful for cache synchronisation, optional. - * @finish: called every time the buffer is passed back from the driver - * to the userspace, also optional. * @vaddr: return a kernel virtual address to a given memory buffer * associated with the passed private structure or NULL if no * such mapping exists. @@ -97,7 +97,7 @@ struct vb2_threadio_data; * associated with the passed private structure or NULL if not * available. * @num_users: return the current number of users of a memory buffer; - * return 1 if the videobuf layer (or actually the driver using + * return 1 if the videobuf2 layer (or actually the driver using * it) is the only user. * @mmap: setup a userspace mapping for a given memory buffer under * the provided virtual memory region. @@ -116,31 +116,33 @@ struct vb2_threadio_data; * map_dmabuf, unmap_dmabuf. */ struct vb2_mem_ops { - void *(*alloc)(struct device *dev, unsigned long attrs, - unsigned long size, - enum dma_data_direction dma_dir, - gfp_t gfp_flags); + void *(*alloc)(struct vb2_buffer *vb, + struct device *dev, + unsigned long size); void (*put)(void *buf_priv); - struct dma_buf *(*get_dmabuf)(void *buf_priv, unsigned long flags); - - void *(*get_userptr)(struct device *dev, unsigned long vaddr, - unsigned long size, - enum dma_data_direction dma_dir); + struct dma_buf *(*get_dmabuf)(struct vb2_buffer *vb, + void *buf_priv, + unsigned long flags); + + void *(*get_userptr)(struct vb2_buffer *vb, + struct device *dev, + unsigned long vaddr, + unsigned long size); void (*put_userptr)(void *buf_priv); void (*prepare)(void *buf_priv); void (*finish)(void *buf_priv); - void *(*attach_dmabuf)(struct device *dev, + void *(*attach_dmabuf)(struct vb2_buffer *vb, + struct device *dev, struct dma_buf *dbuf, - unsigned long size, - enum dma_data_direction dma_dir); + unsigned long size); 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); + void *(*vaddr)(struct vb2_buffer *vb, void *buf_priv); + void *(*cookie)(struct vb2_buffer *vb, void *buf_priv); unsigned int (*num_users)(void *buf_priv); @@ -152,10 +154,14 @@ struct vb2_mem_ops { * @mem_priv: private data with this plane. * @dbuf: dma_buf - shared buffer object. * @dbuf_mapped: flag to show whether dbuf is mapped or not + * @dbuf_duplicated: boolean to show whether dbuf is duplicated with a + * previous plane of the buffer. * @bytesused: number of bytes occupied by data in the plane (payload). - * @length: size of this plane (NOT the payload) in bytes. + * @length: size of this plane (NOT the payload) in bytes. The maximum + * valid size is MAX_UINT - PAGE_SIZE. * @min_length: minimum required size of this plane (NOT the payload) in bytes. - * @length is always greater or equal to @min_length. + * @length is always greater or equal to @min_length, and like + * @length, it is limited to MAX_UINT - PAGE_SIZE. * @m: Union with memtype-specific data. * @m.offset: when memory in the associated struct vb2_buffer is * %VB2_MEMORY_MMAP, equals the offset from the start of @@ -175,6 +181,7 @@ struct vb2_plane { void *mem_priv; struct dma_buf *dbuf; unsigned int dbuf_mapped; + bool dbuf_duplicated; unsigned int bytesused; unsigned int length; unsigned int min_length; @@ -206,11 +213,11 @@ enum vb2_io_modes { * enum vb2_buffer_state - current video buffer state. * @VB2_BUF_STATE_DEQUEUED: buffer under userspace control. * @VB2_BUF_STATE_IN_REQUEST: buffer is queued in media request. - * @VB2_BUF_STATE_PREPARING: buffer is being prepared in videobuf. - * @VB2_BUF_STATE_QUEUED: buffer queued in videobuf, but not in driver. + * @VB2_BUF_STATE_PREPARING: buffer is being prepared in videobuf2. + * @VB2_BUF_STATE_QUEUED: buffer queued in videobuf2, but not in driver. * @VB2_BUF_STATE_ACTIVE: buffer queued in driver and possibly used * in a hardware operation. - * @VB2_BUF_STATE_DONE: buffer returned from driver to videobuf, but + * @VB2_BUF_STATE_DONE: buffer returned from driver to videobuf2, but * not yet dequeued to userspace. * @VB2_BUF_STATE_ERROR: same as above, but the operation on the buffer * has ended with an error, which will be reported @@ -263,22 +270,22 @@ struct vb2_buffer { * after the 'buf_finish' op is called. * copied_timestamp: the timestamp of this capture buffer was copied * from an output buffer. - * need_cache_sync_on_prepare: when set buffer's ->prepare() function - * performs cache sync/invalidation. - * need_cache_sync_on_finish: when set buffer's ->finish() function - * performs cache sync/invalidation. + * skip_cache_sync_on_prepare: when set buffer's ->prepare() function + * skips cache sync/invalidation. + * skip_cache_sync_on_finish: when set buffer's ->finish() function + * skips cache sync/invalidation. + * planes: per-plane information; do not change * queued_entry: entry on the queued buffers list, which holds * all buffers queued from userspace * done_entry: entry on the list that stores all buffers ready * to be dequeued to userspace - * vb2_plane: per-plane information; do not change */ enum vb2_buffer_state state; unsigned int synced:1; unsigned int prepared:1; unsigned int copied_timestamp:1; - unsigned int need_cache_sync_on_prepare:1; - unsigned int need_cache_sync_on_finish:1; + unsigned int skip_cache_sync_on_prepare:1; + unsigned int skip_cache_sync_on_finish:1; struct vb2_plane planes[VB2_MAX_PLANES]; struct list_head queued_entry; @@ -342,8 +349,8 @@ struct vb2_buffer { * describes the requested number of planes and sizes\[\] * contains the requested plane sizes. In this case * \*num_buffers are being allocated additionally to - * q->num_buffers. If either \*num_planes or the requested - * sizes are invalid callback must return %-EINVAL. + * the buffers already allocated. If either \*num_planes + * or the requested sizes are invalid callback must return %-EINVAL. * @wait_prepare: release any locks taken while calling vb2 functions; * it is called before an ioctl needs to wait for a new * buffer to arrive; required to avoid a deadlock in @@ -382,6 +389,12 @@ struct vb2_buffer { * the buffer contents will be ignored anyway. * @buf_cleanup: called once before the buffer is freed; drivers may * perform any additional cleanup; optional. + * @prepare_streaming: called once to prepare for 'streaming' state; this is + * where validation can be done to verify everything is + * okay and streaming resources can be claimed. It is + * called when the VIDIOC_STREAMON ioctl is called. The + * actual streaming starts when @start_streaming is called. + * Optional. * @start_streaming: called once to enter 'streaming' state; the driver may * receive buffers with @buf_queue callback * before @start_streaming is called; the driver gets the @@ -392,7 +405,7 @@ struct vb2_buffer { * by calling vb2_buffer_done() with %VB2_BUF_STATE_QUEUED. * If you need a minimum number of buffers before you can * start streaming, then set - * &vb2_queue->min_buffers_needed. If that is non-zero + * &vb2_queue->min_queued_buffers. If that is non-zero * then @start_streaming won't be called until at least * that many buffers have been queued up by userspace. * @stop_streaming: called when 'streaming' state must be disabled; driver @@ -401,6 +414,10 @@ struct vb2_buffer { * callback by calling vb2_buffer_done() with either * %VB2_BUF_STATE_DONE or %VB2_BUF_STATE_ERROR; may use * vb2_wait_for_all_buffers() function + * @unprepare_streaming:called as counterpart to @prepare_streaming; any claimed + * streaming resources can be released here. It is + * called when the VIDIOC_STREAMOFF ioctls is called or + * when the streaming filehandle is closed. Optional. * @buf_queue: passes buffer vb to the driver; driver may start * hardware operation on this buffer; driver should give * the buffer back by calling vb2_buffer_done() function; @@ -428,8 +445,10 @@ struct vb2_ops { void (*buf_finish)(struct vb2_buffer *vb); void (*buf_cleanup)(struct vb2_buffer *vb); + int (*prepare_streaming)(struct vb2_queue *q); int (*start_streaming)(struct vb2_queue *q, unsigned int count); void (*stop_streaming)(struct vb2_queue *q); + void (*unprepare_streaming)(struct vb2_queue *q); void (*buf_queue)(struct vb2_buffer *vb); @@ -462,13 +481,12 @@ struct vb2_buf_ops { }; /** - * struct vb2_queue - a videobuf queue. + * struct vb2_queue - a videobuf2 queue. * * @type: private buffer type whose content is defined by the vb2-core * caller. For example, for V4L2, it should match * the types defined on &enum v4l2_buf_type. * @io_modes: supported io methods (see &enum vb2_io_modes). - * @alloc_devs: &struct device memory type/allocator-specific per-plane device * @dev: device to use for the default allocation context if the driver * doesn't fill in the @alloc_devs array. * @dma_attrs: DMA attributes to use for the DMA. @@ -500,6 +518,8 @@ struct vb2_buf_ops { * @allow_cache_hints: when set user-space can pass cache management hints in * order to skip cache flush/invalidation on ->prepare() or/and * ->finish(). + * @non_coherent_mem: when set queue will attempt to allocate buffers using + * non-coherent memory. * @lock: pointer to a mutex that protects the &struct vb2_queue. The * driver can set this to a mutex to let the v4l2 core serialize * the queuing ioctls. If the driver wants to handle locking @@ -528,18 +548,38 @@ struct vb2_buf_ops { * @gfp_flags: additional gfp flags used when allocating the buffers. * Typically this is 0, but it may be e.g. %GFP_DMA or %__GFP_DMA32 * to force the buffer allocation to a specific memory zone. - * @min_buffers_needed: the minimum number of buffers needed before + * @min_queued_buffers: the minimum number of queued buffers needed before * @start_streaming can be called. Used when a DMA engine * cannot be started unless at least this number of buffers * have been queued into the driver. + * VIDIOC_REQBUFS will ensure at least @min_queued_buffers + 1 + * buffers will be allocated. Note that VIDIOC_CREATE_BUFS will not + * modify the requested buffer count. + * @min_reqbufs_allocation: the minimum number of buffers to be allocated when + * calling VIDIOC_REQBUFS. Note that VIDIOC_CREATE_BUFS will *not* + * modify the requested buffer count and does not use this field. + * Drivers can set this if there has to be a certain number of + * buffers available for the hardware to work effectively. + * This allows calling VIDIOC_REQBUFS with a buffer count of 1 and + * it will be automatically adjusted to a workable buffer count. + * If set, then @min_reqbufs_allocation must be larger than + * @min_queued_buffers + 1. + * If this field is > 3, then it is highly recommended that the + * driver implements the V4L2_CID_MIN_BUFFERS_FOR_CAPTURE/OUTPUT + * control. + * @alloc_devs: &struct device memory type/allocator-specific per-plane device */ /* * Private elements (won't appear at the uAPI book): * @mmap_lock: private mutex used when buffers are allocated/freed/mmapped * @memory: current memory type used * @dma_dir: DMA mapping direction. - * @bufs: videobuf buffer structures - * @num_buffers: number of allocated/used buffers + * @bufs: videobuf2 buffer structures. If it is non-NULL then + * bufs_bitmap is also non-NULL. + * @bufs_bitmap: bitmap tracking whether each bufs[] entry is used + * @max_num_buffers: upper limit of number of allocated/used buffers. + * If set to 0 v4l2 core will change it VB2_MAX_FRAME + * for backward compatibility. * @queued_list: list of buffers currently queued from userspace * @queued_count: number of buffers queued and ready for streaming. * @owned_by_drv_count: number of buffers owned by the driver @@ -553,8 +593,12 @@ struct vb2_buf_ops { * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for * buffers. Only set for capture queues if qbuf has not yet been * called since poll() needs to return %EPOLLERR in that situation. + * @waiting_in_dqbuf: set by the core for the duration of a blocking DQBUF, when + * it has to wait for a buffer to become available with vb2_queue->lock + * released. Used to prevent destroying the queue by other threads. * @is_multiplanar: set if buffer type is multiplanar * @is_output: set if buffer type is output + * @is_busy: set if at least one buffer has been allocated at some time. * @copy_timestamp: set if vb2-core should set timestamps * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the * last decoded buffer was already dequeued. Set for capture queues @@ -579,6 +623,7 @@ struct vb2_queue { unsigned int uses_qbuf:1; unsigned int uses_requests:1; unsigned int allow_cache_hints:1; + unsigned int non_coherent_mem:1; struct mutex *lock; void *owner; @@ -592,7 +637,8 @@ struct vb2_queue { unsigned int buf_struct_size; u32 timestamp_flags; gfp_t gfp_flags; - u32 min_buffers_needed; + u32 min_queued_buffers; + u32 min_reqbufs_allocation; struct device *alloc_devs[VB2_MAX_PLANES]; @@ -600,8 +646,9 @@ struct vb2_queue { struct mutex mmap_lock; unsigned int memory; enum dma_data_direction dma_dir; - struct vb2_buffer *bufs[VB2_MAX_FRAME]; - unsigned int num_buffers; + struct vb2_buffer **bufs; + unsigned long *bufs_bitmap; + unsigned int max_num_buffers; struct list_head queued_list; unsigned int queued_count; @@ -618,6 +665,7 @@ struct vb2_queue { unsigned int waiting_in_dqbuf:1; unsigned int is_multiplanar:1; unsigned int is_output:1; + unsigned int is_busy:1; unsigned int copy_timestamp:1; unsigned int last_buffer_dequeued:1; @@ -634,8 +682,10 @@ struct vb2_queue { u32 cnt_queue_setup; u32 cnt_wait_prepare; u32 cnt_wait_finish; + u32 cnt_prepare_streaming; u32 cnt_start_streaming; u32 cnt_stop_streaming; + u32 cnt_unprepare_streaming; #endif }; @@ -676,7 +726,7 @@ void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no); void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no); /** - * vb2_buffer_done() - inform videobuf that an operation on a buffer + * vb2_buffer_done() - inform videobuf2 that an operation on a buffer * is finished. * @vb: pointer to &struct vb2_buffer to be used. * @state: state of the buffer, as defined by &enum vb2_buffer_state. @@ -726,7 +776,7 @@ int vb2_wait_for_all_buffers(struct vb2_queue *q); /** * vb2_core_querybuf() - query video buffer information. * @q: pointer to &struct vb2_queue with videobuf2 queue. - * @index: id number of the buffer. + * @vb: pointer to struct &vb2_buffer. * @pb: buffer struct passed from userspace. * * Videobuf2 core helper to implement VIDIOC_QUERYBUF() operation. It is called @@ -738,12 +788,14 @@ int vb2_wait_for_all_buffers(struct vb2_queue *q); * * Return: returns zero on success; an error code otherwise. */ -void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb); +void vb2_core_querybuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb); /** * vb2_core_reqbufs() - Initiate streaming. * @q: pointer to &struct vb2_queue with videobuf2 queue. * @memory: memory type, as defined by &enum vb2_memory. + * @flags: auxiliary queue/buffer management flags. Currently, the only + * used flag is %V4L2_MEMORY_FLAG_NON_COHERENT. * @count: requested buffer count. * * Videobuf2 core helper to implement VIDIOC_REQBUF() operation. It is called @@ -768,15 +820,18 @@ void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb); * Return: returns zero on success; an error code otherwise. */ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory, - unsigned int *count); + unsigned int flags, unsigned int *count); /** * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs * @q: pointer to &struct vb2_queue with videobuf2 queue. * @memory: memory type, as defined by &enum vb2_memory. + * @flags: auxiliary queue/buffer management flags. * @count: requested buffer count. * @requested_planes: number of planes requested. * @requested_sizes: array with the size of the planes. + * @first_index: index of the first created buffer, all allocated buffers have + * indices in the range [first_index..first_index+count-1] * * Videobuf2 core helper to implement VIDIOC_CREATE_BUFS() operation. It is * called internally by VB2 by an API-specific handler, like @@ -791,15 +846,16 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory, * Return: returns zero on success; an error code otherwise. */ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory, - unsigned int *count, + unsigned int flags, unsigned int *count, unsigned int requested_planes, - const unsigned int requested_sizes[]); + const unsigned int requested_sizes[], + unsigned int *first_index); /** * vb2_core_prepare_buf() - Pass ownership of a buffer from userspace * to the kernel. * @q: pointer to &struct vb2_queue with videobuf2 queue. - * @index: id number of the buffer. + * @vb: pointer to struct &vb2_buffer. * @pb: buffer structure passed from userspace to * &v4l2_ioctl_ops->vidioc_prepare_buf handler in driver. * @@ -815,13 +871,23 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory, * * Return: returns zero on success; an error code otherwise. */ -int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb); +int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb); + +/** + * vb2_core_remove_bufs() - + * @q: pointer to &struct vb2_queue with videobuf2 queue. + * @start: first index of the range of buffers to remove. + * @count: number of buffers to remove. + * + * Return: returns zero on success; an error code otherwise. + */ +int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int count); /** * vb2_core_qbuf() - Queue a buffer from userspace * * @q: pointer to &struct vb2_queue with videobuf2 queue. - * @index: id number of the buffer + * @vb: pointer to struct &vb2_buffer. * @pb: buffer structure passed from userspace to * v4l2_ioctl_ops->vidioc_qbuf handler in driver * @req: pointer to &struct media_request, may be NULL. @@ -843,7 +909,7 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb); * * Return: returns zero on success; an error code otherwise. */ -int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb, +int vb2_core_qbuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb, struct media_request *req); /** @@ -907,7 +973,7 @@ int vb2_core_streamoff(struct vb2_queue *q, unsigned int type); * @fd: pointer to the file descriptor associated with DMABUF * (set by driver). * @type: buffer type. - * @index: id number of the buffer. + * @vb: pointer to struct &vb2_buffer. * @plane: index of the plane to be exported, 0 for single plane queues * @flags: file flags for newly created file, as defined at * include/uapi/asm-generic/fcntl.h. @@ -921,7 +987,7 @@ int vb2_core_streamoff(struct vb2_queue *q, unsigned int type); * Return: returns zero on success; an error code otherwise. */ int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type, - unsigned int index, unsigned int plane, unsigned int flags); + struct vb2_buffer *vb, unsigned int plane, unsigned int flags); /** * vb2_core_queue_init() - initialize a videobuf2 queue @@ -1043,7 +1109,7 @@ __poll_t vb2_core_poll(struct vb2_queue *q, struct file *file, size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, loff_t *ppos, int nonblock); /** - * vb2_read() - implements write() syscall logic. + * vb2_write() - implements write() syscall logic. * @q: pointer to &struct vb2_queue with videobuf2 queue. * @data: pointed to target userspace buffer * @count: number of bytes to write @@ -1116,6 +1182,18 @@ static inline bool vb2_fileio_is_active(struct vb2_queue *q) } /** + * vb2_get_num_buffers() - get the number of buffer in a queue + * @q: pointer to &struct vb2_queue with videobuf2 queue. + */ +static inline unsigned int vb2_get_num_buffers(struct vb2_queue *q) +{ + if (q->bufs_bitmap) + return bitmap_weight(q->bufs_bitmap, q->max_num_buffers); + + return 0; +} + +/** * vb2_is_busy() - return busy status of the queue. * @q: pointer to &struct vb2_queue with videobuf2 queue. * @@ -1123,7 +1201,7 @@ static inline bool vb2_fileio_is_active(struct vb2_queue *q) */ static inline bool vb2_is_busy(struct vb2_queue *q) { - return (q->num_buffers > 0); + return !!q->is_busy; } /** @@ -1145,8 +1223,15 @@ static inline void *vb2_get_drv_priv(struct vb2_queue *q) static inline void vb2_set_plane_payload(struct vb2_buffer *vb, unsigned int plane_no, unsigned long size) { - if (plane_no < vb->num_planes) + /* + * size must never be larger than the buffer length, so + * warn and clamp to the buffer length if that's the case. + */ + if (plane_no < vb->num_planes) { + if (WARN_ON_ONCE(size > vb->planes[plane_no].length)) + size = vb->planes[plane_no].length; vb->planes[plane_no].bytesused = size; + } } /** @@ -1208,7 +1293,13 @@ static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q) static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q, unsigned int index) { - if (index < q->num_buffers) + if (!q->bufs) + return NULL; + + if (index >= q->max_num_buffers) + return NULL; + + if (test_bit(index, q->bufs_bitmap)) return q->bufs[index]; return NULL; } |