TODO revision 1.9 
1Some things that need to be done in no particular order:
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3
4Implement isochronous transfer mode.
5
6Implement audio driver.
7
8Do bandwidth accounting.
9
10Use lock manager locks.
11
12Use the pool allocator for TDs et al.
13
14Throw out more USBDI gunk.
15
16Port FreeBSD umass driver.
17
18Make hub driver note transition between self and bus powered state.
19Handle overcurrent conditions.
20
21Make it possible to preallocate DMA buffers to avoid calling the
22memory allocator from an interrupt context.
23
24Move memory allocation and copying to HC independent code.
25
26Use a TD chain in ohci.c to allow transfers > 8K.
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