Date: Thu, 17 Sep 2009 20:09:22 -0700 From: Trevor Blackwell <tlb@tlb.org> To: freebsd-usb@freebsd.org Subject: Transfer size limits Message-ID: <FB232B99-B12C-45F8-A9C8-91B5E0FB973A@tlb.org>
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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.) Currently, I'm setting usbd_xfer_max_len(xfer)==32768. If I could set it large enough for a complete frame (5 MB), it would simplify the logic of my driver. Large transfers didn't work reliably with the -7 USB stack, because of some obscure problem with setting up DMA transfers in the ehci driver with more than a few separate physical regions. -- Trevor Blackwell 650 776 7870 tlb@tlb.org
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