Hi,
After getting through the compilation issues regarding the uvc_debugfs, I am
now facing another problem, which I think is more generic.
The FreeBSD port of the Linux UVC driver, webcamd, gives a division by zero
inside the UVC driver, because it does not properly check if the returned SOF
counter is the same like the previous one. This can also happen on Linux if
the UVC capable device is plugged exactly when the EHCI/OHCI/UHCI SOF counter
is equal to zero!
Also please note that the SOF counter will only be updated after the each
completed ISOCHRONOUS transfer on FreeBSD, due to limitations in LibUSB.
Debug info:
(gdb) list
651 else if (sof > mean + (1024 << 16))
652 sof -= 2048 << 16;
653
654 y = (u64)(y2 - y1) * (u64)sof + (u64)y1 * (u64)x2
655 - (u64)y2 * (u64)x1;
656 y = div_u64(y, x2 - x1);
657
658 div = div_u64_rem(y, NSEC_PER_SEC, &rem);
659 ts.tv_sec = first->host_ts.tv_sec - 1 + div;
660 ts.tv_nsec = first->host_ts.tv_nsec + rem;
(gdb)
Program received signal SIGFPE, Arithmetic exception.
[Switching to Thread 80100a3c0 (LWP 100096/webcamd)]
0x00000000005e9337 in div_u64 (rem=71210779720321120, div=0)
at kernel/linux_func.c:1649
1649 {
(gdb) bt
#0 0x00000000005e9337 in div_u64 (rem=71210779720321120, div=0)
at kernel/linux_func.c:1649
#1 0x00000000005169f7 in uvc_video_clock_update (stream=0x8010bf500,
v4l2_buf=0x801138a00, buf=0x801138a00)
at media_tree/drivers/media/video/uvc/uvc_video.c:656
#2 0x00000000005125c3 in uvc_buffer_finish (vb=Variable "vb" is not
available.
)
at media_tree/drivers/media/video/uvc/uvc_queue.c:114
#3 0x00000000004ae76a in vb2_dqbuf (q=0x8010bf5b8, b=0x7fffff1f9d30,
nonblocking=0 '\0') at media_tree/drivers/media/video/videobuf2-
core.c:1334
#4 0x000000000051236f in uvc_dequeue_buffer (queue=0x8010bf5b8,
buf=0x7fffff1f9d30, nonblocking=0)
at media_tree/drivers/media/video/uvc/uvc_queue.c:193
#5 0x0000000000513c50 in uvc_v4l2_do_ioctl (file=0x80111d418, cmd=3227014673,
arg=0x7fffff1f9d30) at media_tree/drivers/media/video/uvc/uvc_v4l2.c:958
#6 0x0000000000444780 in video_usercopy (file=0x80111d418, cmd=3227014673,
arg=65536, func=0x513050 <uvc_v4l2_do_ioctl>)
at media_tree/drivers/media/video/v4l2-ioctl.c:2456
#7 0x0000000000443b40 in v4l2_ioctl (filp=0x80111d418, cmd=3227014673,
arg=65536) at media_tree/drivers/media/video/v4l2-dev.c:339
#8 0x00000000005ea4aa in linux_ioctl (handle=0x80111d400, fflags=0,
cmd=3227014673, arg=0x10000) at kernel/linux_file.c:120
#9 0x00000000005ef01a in v4b_ioctl (cdev=Variable "cdev" is not available.
) at webcamd.c:261
#10 0x0000000800a249e6 in cuse_wait_and_process ()
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