Date: Fri, 18 Sep 2009 12:58:34 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-usb@freebsd.org Subject: Re: Transfer size limits Message-ID: <200909181258.35957.hselasky@c2i.net> In-Reply-To: <FB232B99-B12C-45F8-A9C8-91B5E0FB973A@tlb.org> References: <FB232B99-B12C-45F8-A9C8-91B5E0FB973A@tlb.org>
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On Friday 18 September 2009 05:09:22 Trevor Blackwell wrote: > What's the largest practical bulk transfer size in the -8 USB stack? > I'm currently transferring frames through a UE_BULK pipe from a > Mightex camera (it uses bulk, not isochronous.) You have to check what busdma supports. USB uses 32-bit transfer lenghts. Typically 64KByte blocks will give you a decent performance. What is your performance requirement? --HPS
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