my usb camera works fine under linux.
but in linux it can not get the data.
i custom the V4L2 driver for the camera.
everything seems good,but just can not
read data from the camera.
i use the Isochronous mode to get the data
from the camera. in the complete handler of
the struct urb that been submited . i check
the return status of the iso packet in the
urb ,and the status is success (0). but the
actual length of the transfer_buffer is 0
which means no data.
/*-----the code in the complete handler of urb*/
if(urb->status!=-ENOENT)
{
for(step=0;step<FRAMES_PER_DESC;step++)
{
PDEBUG("the step packe %d size is %d\n",step,urb-
>iso_frame_desc[step].actual_length);
if(!urb->iso_frame_desc[step].status)
{
len=urb->iso_frame_desc[step].actual_length;
if(len<=pktsz)
memcpy(buf+dst,buf+urb->iso_frame_desc[step].offset,len);
dst+=len;
}
else
{
/*this packet is error*/
PDEBUG("PACKET STATE ERROR
states:%d\n",urb->iso_frame_desc[step].status);
}
}
/*and the output of the dmesg and /var/log/messages*/
Jun 3 21:27:22 Sky kernel: DC DEBUG: get from frame
371 len 0 buflen 8184
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 0
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 1
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 2
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 3
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 4
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 5
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 6
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: the step packe 7
size is 0
Jun 3 21:27:22 Sky kernel: DC DEBUG: read one buffer
done len 0
/****************************************************/
can anybody gei wo some advise to help me figure out
the error?
thank u for help
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