What is wrong with FreeBSD and USB Support

Markus Rechberger mrechberger at gmail.com
Mon Mar 6 10:48:00 UTC 2017

On Mon, Mar 6, 2017 at 11:41 AM, Hans Petter Selasky <hps at selasky.org> wrote:
> 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.

Unless we're talking about something different here I'm always
generating single 15k (or bigger) requests with Linux and request them
at once. I do not have to generate N 512byte URBs to request 15k.
And the 15k (or bigger) only complete once they're fully filled.

> --HPS

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