Hi, Currently I got a philips webcam (type 740), which can be driven by
pwc in Linux.
Now I want to write my own program to test the isochronus transfer
function of the device, not using the pwc driver.
So I found out the device node in /proc/bus/usb/* and open it, then use
such an ioctl(fd, USBDEVFS_SUBMITURB, struct userspace_urb...) call to
send a isoc urb to the device.
My urb includes fields like below:
type = 0 (ISOC transfer)
endpoint = 0x85 (ISOC IN endpoint)
status = 0;
flags = 2 (USBDEVFS_URB_ISO_ASAP)
buffer = isoc_buf (isoc_buf was defined as char isoc_buf[9600])
buffer_length = sizeof (isoc_buf)
actual_length = 0;
start_frame = 0;
number_of_packets = 10
error_count = 0;
signr = 0
usercontext = the address of urb structure
The wMaxPacketSize of the isoc endpoint is 960.
while I send out this urb, I hope to receive some data from the webcam
device. but I receive nothing, the actual_length = 0.
Could anybody tell me why?
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