Hi,
I'm currently coding a device driver for a high speed device.
Unfortunately,
the test have shown, that the transfer rate is real slow.
The code is as follows:
urb = usb_alloc_urb( 0, GFP_KERNEL );
.....
usb_fill_bulk_urb( urb, usb_dev, pipe, data, len,
wcam_usb_api_blocking_completion, context );
init_completion( &sbuf->done );
.....
urb->actual_length = 0;
status = usb_submit_urb(urb, GFP_ATOMIC);
.....
if ( status == 0 )
{
wait_for_completion( &sbuf->done );
}
The memory to transfer is 307200 Bytes, the enpoint transfers up to 320
Byte.
BTW, is it possible to increase the Bulk transfersize beyond the 512 Bytes
?
Now, what I get is, that the completion handler is called 960 times in 120
ms, which means
that the driver uses a single microframe to transfer 320 Bytes.
So my question is: How do I have to configure the bulk transfer to get the
maximum speed ?
TIA,
Franz
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