What is wrong with FreeBSD and USB Support

Hans Petter Selasky hps at selasky.org
Mon Mar 6 10:42:32 UTC 2017

On 03/06/17 11:37, Markus Rechberger wrote:
> Are you sure? As from some of my signal analyzer dumps I do think that
> all those systems support
> multiple transfers within one completion event. I always request
> multiple frames within one request on those systems and they complete
> at once. And they only complete once all the buffers are filled.

Yes, I'm 100% sure. If you look at their APIs you will have to submit 
individual jobs as a URB in Linux. If you want to send 128 x 333 bytes 
as 333 byte sized USB HighSpeed BULK packets, then Linux/MacOS and 
Windows force you to generate 128 URBs/Jobs to send the 128 packets. In 
FreeBSD a single USB transfers can send 128x 333 bytes. Only in the case 
where you send full-sized packets having an optional short-sized packet 
in the end, Linux/MacOS and Windows allows you to accumulate them into a 
single completion event.


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