The cache should be invalidated when transfering ownership of a buffer
to the device. Otherwise the writeback of dirty cache lines can
corrupt the hardware written data.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: Jan Weitzel <j.weitzel@phytec.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>