[PATCH][RFC] usbatm.[ch]: cleanup and OAM F5 loopback

Roman Kagan rkagan at mail.ru
Sun Mar 13 16:02:47 EST 2005

On Sun, Mar 13, 2005 at 12:31:59PM +0100, matthieu castet wrote:
> I don't know, but what is strange is that if I force my modem to 
> synchronize to a lower speed 6500kbits/s, and if I only download there 
> aren't any error. If I start uploading there are errors.
> In 7000kits/s there are always errors even if I download only.

Are you doing your tests in 2.6.10 or 2.6.11?  There've been a number of
changes in usb hcd drivers which might affect performance.

Besides, can you please add printing of urb status to
usbatm_complete_receive and usbatm_complete_send, to see if the errors
happen during transfer and are reported by the hcd but ignored by
usbatm, or on the contrary the modem happily sends garbage?

> Maybe because bulk is reliable, the modem should keep data in his memory 
> before receiving an ack and it is very painful because it had a small 
> memory and haven't enough memory for the atm frame that are coming from 
> adsl.

Dunno...  I'd suggest to play with the size and number of buffers and
urbs, it may reveal some correlation with the modem behavior.

BTW how does firmware swapping interfere with the data transfers?  I
can't imagine the modem reloading a different part of firmware for every
transmission or reception without influencing the performance.


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