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

matthieu castet castet.matthieu at free.fr
Sun Mar 13 06:31:59 EST 2005

Hi Roman

Roman Kagan wrote:
> On Sat, Mar 12, 2005 at 11:10:03PM +0100, matthieu castet wrote:
>>Well, may be it is the sagem that don't work well with bulk mode, but 
>>when it is in high speed mode, if you reach a limit (200-300kb/s), the 
>>modem produce lot's of error, and the atm data trame are broken (crc 
>>error, bogus pdu_length, ...). So because of these errors, the modem 
>>never reach the maximun rate.
>>In iso rate it work at 700kb/s with no problem.
> That's strange...  It is the iso transfers which are supposed to be
> unreliable, as opposed to bulk.  I wonder if the errors happen in the
> modem or in the host controller (e.g. VIA chipsets are said to often
> misbehave).
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.

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 

> BTW what do you call "high speed mode"?  Does it support USB 2.0 high
> speed (480 Mbps)?
No, I was referring to the modem "high speed mode" : in bulk mode if the 
rate in more than 1024kbits/s, the modem change an internal timeout.


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