Hi Hans, On Wednesday 15 February 2012 18:27:29 Hans Petter Selasky wrote: > 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! It's a know bug (at least to me :-)). Does http://git.linuxtv.org/pinchartl/uvcvideo.git/commit/5c97eb2eb9c45dad8825de7754ceb33699451978 fix your problem ? I've queued that patch in my tree for v3.4. > 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 () -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
