Hi,
We are now nearly complete porting our camera driver to align with soc-camera framework, however, we encounter a problem when it works with our application during switch format from preview to still capture, application's main calling sequence is as follow:
1) s_fmt /* preview @ YUV, VGA */
2) request buffer (buffer count = 6)
2) queue buffer
3) stream on
4) q-buf, dq-buf...
5) stream off
6) s_fmt /* still capture @ jpeg, 2592x1944*/
7) request buffer (buffer count = 3)
8) same as 3)->5)...
The point is in soc_camera_s_fmt_vid_cap() {
if (icd->vb_vidq.bufs[0]) {
dev_err(&icd->dev, "S_FMT denied: queue initialised\n");
ret = -EBUSY;
goto unlock;
}
}
We didn't find vb_vidq.bufs[0] be free, (it is freed in videobuf_mmap_free(), and in __videobuf_mmap_setup, but no one calls videobuf_mmap_free(), and in __videobuf_mmap_setup it is freed at first and then allocated sequentially), so we always fail at calling s_fmt.
My idea is to implement soc_camera_reqbufs(buffer count = 0), to provide application opportunity to free this buffer node, refer to v4l2 spec, http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-reqbufs.html
"A count value of zero frees all buffers, after aborting or finishing any DMA in progress, an implicit VIDIOC_STREAMOFF."
What do you think?
Any ideas will be appreciated!
Thanks!
Qing Xu
Email: qingx@xxxxxxxxxxx
Application Processor Systems Engineering,
Marvell Technology Group Ltd.
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