hi
2012/2/16 Hans Petter Selasky <hsela...@c2i.net>:
> 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 ()
Maybe it is better forwarding this mail to uvc mail list
--
Regards,
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