/*
* WUSB Wire Adapter
* Data transfer and URB enqueing
*
* Copyright (C) 2005-2006 Intel Corporation
* Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
*
* How transfers work: get a buffer, break it up in segments (segment
* size is a multiple of the maxpacket size). For each segment issue a
* segment request (struct wa_xfer_*), then send the data buffer if
* out or nothing if in (all over the DTO endpoint).
*
* For each submitted segment request, a notification will come over
* the NEP endpoint and a transfer result (struct xfer_result) will
* arrive in the DTI URB. Read it, get the xfer ID, see if there is
* data coming (inbound transfer), schedule a read and handle it.
*
* Sounds simple, it is a pain to implement.
*
*
* ENTRY POINTS
*
* FIXME
*
* LIFE CYCLE / STATE DIAGRAM
*
* FIXME
*
* THIS CODE IS DISGUSTING
*
* Warned you are; it's my second try and still not happy with it.
*
* NOTES:
*
* - No iso
*
* - Supports DMA xfers, control, bulk and maybe interrupt
*
* - Does not recycle unused rpipes
*
* An rpipe is assigned to an endpoint the first time it is used,
* and then it's there, assigned, until the endpoint is disabled
* (destroyed [{h,d}wahc_op_ep_disable()]. The assignment of the
* rpipe to the endpoint is done under the wa->rpipe_sem semaphore
* (should be a mutex).
*
* Two methods it could be done:
*
* (a) set up a timer every time an rpipe's use count drops to 1
* (which means unused) or when a transfer ends. Reset the
* timer when a xfer is queued. If the timer expires, release
* the rpipe [see rpipe_ep_disable()].
*
* (b) when looking for free rpipes to attach [rpipe_get_by_ep()],
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