Hi Ricardo,
On Sunday 11 May 2008, Ricardo Ferreira wrote:
> Hi, thanks for the response,
>
> On Sunday 11 May 2008 09:15:05 Laurent Pinchart wrote:
> > Hi Ricardo,
> >
> > On Wednesday 07 May 2008, Ricardo Ferreira wrote:
> > > Hello all,
> > >
> > > I stumbled upon a problem when using your driver. It seems that it
> > > blocks on the first VIDIOC_DQBUF ioctl.
> > >
> > > I first noticed it in my code using the latest debian linux-uvc-source
> > > on an amd64 2.6.24 kernel. I assumed it was my problem so I tried
> > > luvcview and noticed that there was always a 2 second block the first
> > > time that same ioctl was called, but it worked flawlessly after that.
> > >
> > > After grabing your latest svn driver, luvcview stopped working,
> > > blocking on the first call to VIDIOC_DQBUF.
> > >
> > > I have an integrated webcam:
> > > Bus 006 Device 003: ID 05c8:0103 Cheng Uei Precision Industry Co., Ltd
> > > (Foxlink)
> > >
> > > since I never heard of this manufacturer, I tried a phillips spc1000nc
> > > freshly bought. The results were exactly the same.
> > >
> > > Do you think it has to do with the driver, this particular kernel,
> > > amd64 (had some other compatibility issues because of this in the
> > > past), or anything else?
> >
> > Could you please retry with r206 and r207 and compare the results ? r207
> > introduces a patch to drop incomplete frames.
>
> Yes, that is exactly were it breaks. r206 has that 1-2 second delay the
> first time DQBUF is called, but after that it is perfect. in r207 the first
> call to DQBUF never returns.
Thanks for your fast reply.
> > If reverting to r206 helps, I'll ask you to try a patch to get more
> > information about the issue.
>
> sure, whatever helps.
I've attached a patch to this e-mail. Could you please apply it, load the
driver with the trace parameter set to 143 and report the kernel log
messages ?
Best regards,
Laurent Pinchart
Index: uvc_queue.c
===================================================================
--- uvc_queue.c (revision 207)
+++ uvc_queue.c (working copy)
@@ -447,6 +447,9 @@
unsigned long flags;
if (queue->drop_incomplete && buf->buf.length != buf->buf.bytesused) {
+ uvc_trace(UVC_TRACE_FRAME, "incomplete buffer (%u bytes, "
+ "expected %u)\n", buf->buf.bytesused,
+ buf->buf.length);
buf->state = UVC_BUF_STATE_QUEUED;
buf->buf.bytesused = 0;
return buf;
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