Hello,

I am working with usb pwc webcam driver.

I am trying to set alternate setting different than the
default one.

To achieve it,I had tried to call usb_set_interface()
with altenate setting 1 (different than default.)

The usb_set_interface() call succeeds (I can verify it by
making another call to usb_set_interface() as was suggested bt
Alan Stern in this forum ;
see : http://marc.theaimsgroup.com/?l=linux-usb-devel&m=108860856823230&w=2).




the result is :
I do reach the pwc_isoc_handler (this is the completion
callback).

The problem is that it reaches pwc_isoc_handler in an endless loop ,
instead of exiting after some iterations, as in the normal situation.

When getting iso packets, the data is in urb->iso_frame_desc array.

The actual_length field of iso_frame_desc denotes the length of the packet.

By debugging I saw that it reaches the handler with
actual_length=0 ; the status, however, is 0 (success).

urb->number_of_packets is 10.

After 31 interations, the actual_length is 3  , but the status is -75 ;
(this status means EOVERFLOW ; Value too large for defined data type )


(in the default case , the actual length is 291, 1 less than tha MxPS of the default
alternate setting , which is 292).


Any idea what the problem can be ?

regards,
John

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