Hi Laurent,
On 07.04.2014 01:37, Laurent Pinchart wrote:
Hi Thomas,
On Friday 04 April 2014 20:01:33 Scheuermann, Mail wrote:
Hi Laurent,
I've done the following:
echo 3 >/sys/module/videobuf2_core/parameters/debug
and found in /var/log/kern.log after starting my program:
[239432.535077] vb2: Buffer 0, plane 0 offset 0x00000000
[239432.535080] vb2: Buffer 1, plane 0 offset 0x001c2000
[239432.535082] vb2: Buffer 2, plane 0 offset 0x00384000
[239432.535083] vb2: Allocated 3 buffers, 1 plane(s) each
[239432.535085] vb2: qbuf: userspace address for plane 0 changed,
reacquiring memory
[239432.535087] vb2: qbuf: failed acquiring userspace memory for plane 0
This confirms everything is working properly up to the point where videobuf2-
vmalloc fails to acquire the user pointer memory. The problem comes from
vb2_vmalloc_get_userptr() in drivers/media/v4l2-core/videobuf2-vmalloc.c.
Unfortunately that function lacks debugging. Are you familiar enough with
kernel programming to add printk statements there and see where it fails ?
I was able to put some debug output in vb2_vmalloc_get_userptr.
A call to 'vb2_get_contig_userptr' failed.
I will also put some debug code there to get more information.
[239432.535088] vb2: qbuf: buffer preparation failed: -22
[239432.535128] vb2: streamoff: not streaming
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