[PATCH] eagle bulk mode bugfix

[Duncan Sands]

Hi Staszek,

> Hi all, this patch fix eagle bulk mode bug. 
> 
> Bug consist in atm cells can coming partially in two consecutive
> usrbs or telling it differently urb buffer size can be not multiple of 
> atm cell size. Patch simply catch such case and save partial
> incoming atm cell in additional buffer, when next urbs comm in, 
> fill additional buffer with rest of cell and process remain data 
> normally.
> 
> Bug can't be solved in firmwere as sources are not available
> (I'm even not sure is firmware problem maybe it's hardwere related).
> 
> Patch should speed up internet connection for ueagle-atm
> in bulk mode and should have no influence of other usbatm subdrivers.
> 
> Indentation in usbatm_extract_one_cell() was preserved
> as in usbatm_extract_cells() for easiest patch reading.
> 
> Please test/review. Patch should cleanly apply to today 
> usbatm CVS snapshot.

something like this is also needed for the speedtouch when using isoc
urbs: when using bulk, the urb buffer size can be arranged to be a
multiple of both the stride and the maxpacket size; but with isoc,
the maxpacket size is so big that you would have to use absurdly
sized buffers to ensure this.  Since you are basically obliged to
have the buffer size be a multiple of the maxpacket size, that
means that you have to drop the requirement that buffer holds an
integral number of ATM cells - and your patch is needed.  In any
case, it was always dubious to rely on the modem sending complete
ATM cells.

I plan to spend most of tomorrow working on the driver, so
hopefully I will commit it then.

Ciao,

Duncan.