Re: [Linux-uvc-devel] rev 4 test with kernel smp Intel x86_64

[michel X. <mx...@ma...>]

Le Mercredi 4 Janvier 2006 23:02, Laurent Pinchart a écrit :
> Hi Michel,
>
> > Just test the rev 4 with my HP zd8000 P4 64 bits 3Go with a smp kernel,
> > graphic card ATI Mobility X600 and the uvcview SDL grabber
> > the good news
> > the driver work fine with all jpeg/size
> > SDL yuv overlay never crash :)
> > the bad news :
> > driver return EIO on VIDIOC_DQBUF with all yuyv palette in my grabbing
> > routine. SDL open a black screen but did not crash the box :)
> > to be sure
> > tested with my Athlon 2200+ Nvidia card, all size/palette are working
> > like a charm .
>
> -EIO means that the buffer has been marked as erroneous. Either because the
> URB completion handler received more data than expected or because it
> received a non-zero status. Could you check dmesg to see if it prints a
> debug message ? If not, please have a look at uvc_video_complete and add
> printks to see where it fails.
>
> Laurent Pinchart
Laurent,
I am still trying to figure out where the corruption come from on the SMP box. 
After some usefull uvc_printk() and moving some part of code from 
uvc_video_decode() to uvc_video_complete() i can make MJPEG working or not :(
even if my code do nothing exept take the value in the iso desc buffer brr .

On each usb packet desc (data[0]) the first field reffer to the packet header 
lenght ?with yuyv palette the stream start with that field set to 0 then 
toggle to 12 in the stream and  for a short  times ( ~2 usb packet) goes to 0 
when the packet length is full ? this feature only appear on yuyv palette.
On a UP box this field is constant and always egal to 12. 
I think we are not getting the right data from the urb buffer here :(
In my experiment i have get some good kernel crash :)  I suspect on restart 
the last synchro bit in the queue is not reset or maybe my grabber is wrong 
and need to dequeue all buffers on stop ?  
-- 
Michel Xhaard
http://mxhaard.free.fr