Hi Sebastian,

On Fri, May 8, 2015 at 4:13 AM, Sebastian Andrzej Siewior
[off-list ref] wrote:

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

This basically reverts commit 068500e08dc8 ("serial: imx: initialized
DMA w/o HW flow enabled") simply because it does not work.
I tested it on various IMX6 boards and the default SDMA firmware, that is
included in ROM, does not work properly. The SDMA interrupt counter does
not stop increment (which means the SDMA does not stop working) and I see
a lot of 0x00 (sometimes other bytes) which are added to the tty buffer
which are not part of the data transfer.
Jiada claimed that there is a firmware which makes it work but failed to
provide me a link to the firmware. All he said was that it can not be
shipped as part of the kernel due to license issues. I've found one
firmware in the FSL-tree but this firmware causes only TTY-overflows and
*no* data is transmitted.

Currently I see no other way out.

Could you please test Philipp's patch?
http://marc.info/?l=linux-serial&m=143202566332128&q=raw

It worked on my tests and DMA still works with his patch, so I would
prefer his solution.

Thanks,

Fabio Estevam