not stop increment (which means the SDMA does not stop working or the ACK
is 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 a firmware
blob in the FSL-tree but this firmware causes only TTY-overflows an *no*
data is transmitted.

Currently I see no other way out.

Fixes: 068500e08dc8 ("serial: imx: initialized DMA w/o HW flow enabled")
Cc: Fabio Estevam <redacted>
Cc: Jiada Wang <redacted>
Cc: nicolae.rosia@gmail.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/tty/serial/imx.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 8aff0b4d8ddf..e686c75fa4dc 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c

@@ -1113,11 +1113,6 @@ static int imx_startup(struct uart_port *port)

        writel(temp & ~UCR4_DREN, sport->port.membase + UCR4);

-       /* Can we enable the DMA support? */
-       if (is_imx6q_uart(sport) && !uart_console(port) &&
-           !sport->dma_is_inited)
-               imx_uart_dma_init(sport);
-
        spin_lock_irqsave(&sport->port.lock, flags);
        /* Reset fifo's and state machines */
        i = 100;

@@ -1308,6 +1303,17 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
                        } else {
                                ucr2 |= UCR2_CTSC;
                        }
+
+                       /*
+                        * Can we enable the DMA support? Be aware that
+                        * at least IMX6 needs to load external SDMA firmware in
+                        * order work properly. The in-ROM firmware is not
+                        * wokring properly.