Hi,
We are writing a USB Bluetooth driver with SCO
support using a sample hardware that we have. We have
run into some questions regarding the implmentation of
ISOC/SCO support for the card. While enumerating we
are getting as many endpoints on interface 1 as
mentioned in the Bluetooth spec. We use alternate
setting 2 (where max packet size is 17).
We fill the isoc urb as shown below:
pdrvobj->isoc_in_urb->context = pdrvobj;
pdrvobj->isoc_in_urb->dev = pdrvobj->dev;
pdrvobj->isoc_in_urb->pipe =
usb_rcvisocpipe(pdrvobj->dev,
pdrvobj->isoc_in_ep->bEndpointAddress);
pdrvobj->isoc_in_urb->complete = read_isoc_callback;
pdrvobj->isoc_in_urb->transfer_buffer_length = size =
pdrvobj->isoc_in_ep->wMaxPacketSize * 10;
pdrvobj->isoc_in_urb->transfer_buffer =
pdrvobj->isoc_in_buffer;
pdrvobj->isoc_in_urb->transfer_flags = USB_ISO_ASAP;
fill_frame_settings(pdrvobj->isoc_in_urb, size,
pdrvobj->isoc_in_ep->wMaxPacketSize); //
fill_frame_settings () is where length and offset of
each frame is set.
retval = usb_submit_urb(pdrvobj->isoc_in_urb);
We have the following questions:
o The read_isoc_callback gets called as soon as we
finish usb_submit_urb call. Is this normal ?
o Whenever the read_isoc_callback gets called the
urb->dev field is set to NULL and we have to reassign
urb->dev = pdrvobj->dev
Why does happen ? Do we need to reassign any of the
fields other than urb->dev ?
o The callback gets called even before any ISOC
transfer starts and we get urb->actual_length = 0 in
every iteration of the read_isoc_callback. Also
urb->iso_frame_desc[i].actual_length = 0 for all
frames.
What might be wrong ?
o After the successful creation of a SCO connection
and actual SCO data expected from the other end we get
the same behaviour as stated above. No data actually
arrives in the read_isoc_callback.
Thanks
'a'
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