Dear Alan,
maybe there is a bug in VMWare. If so, there must be either a bug in the
firmware or in the uvc module, since the camera is not working on native
Linux without the nodrop option.
I verified the following. In uvc_video.c at line 595
if (urb->iso_frame_desc[i].status < 0) {
uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "
"lost (%d).\n", urb->iso_frame_desc[i].status);
/* Mark the buffer as faulty. */
if (buf != NULL)
buf->error = 1;
continue;
}
a complete URB is dropped, if one of the packets is erroneous. The
format is uncompressed in my case. The comparison at line 627
buf->buf.length != buf->buf.bytesused
will set
buf->error = 1;
for almost every URB.
I added one line after above mentioned block for testing purposes:
if (urb->iso_frame_desc[i].status < 0) {
uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "
"lost (%d).\n", urb->iso_frame_desc[i].status);
/* Mark the buffer as faulty. */
if (buf != NULL)
buf->error = 1;
continue;
}
buf->error = 0;
resetting buf->error in order to receive at least the remaining packets
with no status flag < 0.
So, I just discard erroneous packets, not the whole URB.
Loading uvcvideo with this modification provides a data stream as
expected, even without the nodrop option. The syslog trace now looks
like below. You can see that for every URB three isochronous frames are
lost, and 29 packets are received. Are you sure that this is not a
firmware problem?
Best regards,
Stefan May
Oct 27 17:41:06 Brutus kernel: [53.512200] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.512210] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_DQBUF)
Oct 27 17:41:06 Brutus kernel: [53.512214] uvcvideo: Dequeuing buffer 1
(4, 221184 bytes).
Oct 27 17:41:06 Brutus kernel: [53.512217] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_QBUF)
Oct 27 17:41:06 Brutus kernel: [53.512219] uvcvideo: Queuing buffer 1.
Oct 27 17:41:06 Brutus kernel: [53.519804] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.524185] uvcvideo: Frame complete (EOF
found).
Oct 27 17:41:06 Brutus kernel: [53.524194] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.524195] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.524197] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.524217] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.524226] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_DQBUF)
Oct 27 17:41:06 Brutus kernel: [53.524230] uvcvideo: Dequeuing buffer 2
(4, 221184 bytes).
Oct 27 17:41:06 Brutus kernel: [53.524232] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_QBUF)
Oct 27 17:41:06 Brutus kernel: [53.524234] uvcvideo: Queuing buffer 2.
Oct 27 17:41:06 Brutus kernel: [53.530820] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.536178] uvcvideo: Frame complete (EOF
found).
Oct 27 17:41:06 Brutus kernel: [53.536204] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.536215] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_DQBUF)
Oct 27 17:41:06 Brutus kernel: [53.536220] uvcvideo: Dequeuing buffer 3
(4, 221184 bytes).
Oct 27 17:41:06 Brutus kernel: [53.536223] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_QBUF)
Oct 27 17:41:06 Brutus kernel: [53.536225] uvcvideo: Queuing buffer 3.
Oct 27 17:41:06 Brutus kernel: [53.537765] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.540155] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.540157] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.540158] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.552163] uvcvideo: Frame complete (EOF
found).
Oct 27 17:41:06 Brutus kernel: [53.552173] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.552174] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.552175] uvcvideo: USB isochronous
frame lost (-71).
Oct 27 17:41:06 Brutus kernel: [53.552218] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.552227] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_DQBUF)
Oct 27 17:41:06 Brutus kernel: [53.552231] uvcvideo: Dequeuing buffer 0
(4, 221184 bytes).
Oct 27 17:41:06 Brutus kernel: [53.552234] uvcvideo:
uvc_v4l2_ioctl(VIDIOC_QBUF)
Oct 27 17:41:06 Brutus kernel: [53.552236] uvcvideo: Queuing buffer 0.
Oct 27 17:41:06 Brutus kernel: [53.553636] uvcvideo: uvc_v4l2_poll
Oct 27 17:41:06 Brutus kernel: [53.564163] uvcvideo: Frame complete (EOF
found).
Am 26.10.2012 19:10, schrieb Alan Stern:
On Fri, 26 Oct 2012, Stefan May wrote:
I saw different bmVideoStandards with lsusb. It is the only parameter
with a different value on both sides. Meanwhile, I found a way to make
the camera work. I need to use the load option nodrop=1 in the host, but
not in the guest.
I have no idea why UVC sees incomplete frames only on host side. It is
definitely a firmware problem. Could you imagine what was not respected
there, so that almost every packet is dropped?
I don't think it is a firmware problem. It is a bug in VMWare.
Alan Stern
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