On Tue, Jan 28, 2014 at 01:05:10PM +0100, Arnd Bergmann wrote:

Ok, thanks for clearing up my mistake. However, the argument remains:
the direction doesn't need to be in the DT DMA descriptor since it
gets set by software anyway.

Yes - for full-duplex, it's implied, since you have one DMA request
(and therefore virtual channel) for memory-to-device and another for
device-to-memory.

-- 
FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up.  Estimation
in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad.
Estimate before purchase was "up to 13.2Mbit".