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v4l2: Introduce helper to request buffers

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Although this is not needed when using the combination of CREATE_BUFS and
QUERYBUF V4L2 ioctls (as currently done) to allocate and prepare buffers,
the REQBUF ioctl is useful to liberate the buffers after use.

This introduces a helper for this purpose.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
This commit is contained in:
Paul Kocialkowski
2018-07-19 15:03:47 +02:00
parent d2357862f8
commit 72c22a3bce
2 changed files with 22 additions and 0 deletions
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src/v4l2.c
+20
View File
@@ -188,6 +188,26 @@ int v4l2_query_buffer(int video_fd, unsigned int type, unsigned int index,
return 0;
}
int v4l2_request_buffers(int video_fd, unsigned int type,
unsigned int buffers_count)
{
struct v4l2_requestbuffers buffers;
int rc;
memset(&buffers, 0, sizeof(buffers));
buffers.type = type;
buffers.memory = V4L2_MEMORY_MMAP;
buffers.count = buffers_count;
rc = ioctl(video_fd, VIDIOC_REQBUFS, &buffers);
if (rc < 0) {
request_log("Unable to request buffers: %s\n", strerror(errno));
return -1;
}
return 0;
}
int v4l2_queue_buffer(int video_fd, int request_fd, unsigned int type,
unsigned int index, unsigned int size,
unsigned int buffers_count)
src/v4l2.h
+2
View File
@@ -41,6 +41,8 @@ int v4l2_create_buffers(int video_fd, unsigned int type,
int v4l2_query_buffer(int video_fd, unsigned int type, unsigned int index,
unsigned int *lengths, unsigned int *offsets,
unsigned int buffers_count);
int v4l2_request_buffers(int video_fd, unsigned int type,
unsigned int buffers_count);
int v4l2_queue_buffer(int video_fd, int request_fd, unsigned int type,
unsigned int index, unsigned int size,
unsigned int buffers_count);