Control V4L2/VB2 Buffer Allocation?

Question

I am trying to write a V4L2 compliant driver for a special camera device i have, but the device doesn't seem particularly friendly with V4L2's buffer system. Instead of the separately allocated buffers, it wants a single contiguous block of memory capable of holding a set # of buffers (usually 4), and it then provides a status register telling you which is the latest (updated after each frame is DMA'ed to the host). So it basically needs only a single large DMA allocated memory chunk to work with, not 4 most-likely separated.

How can I use this with V4L? Everything I see about VIDIOC_CREATE_BUFS, VIDIOC_REQBUFS and such does internal allocation of the buffers, and I can't get anything V4L-based (like qv4l2 to work without a successful QBUF and DQBUF that uses their internal structure.

How can this be done?

Answer 1

Just for completion, I finally found a solution in the "meye" driver. I removed everything VB2 and wrote my own reqbuf, querybuf, qbuf, and dqbuf, along with my own mmap routines to handle the allocation. And it all works!