--- /dev/null
+From 6df765dca378bddf994cfd2044acafa501bd800f Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
+Date: Wed, 24 May 2017 21:38:46 +0200
+Subject: serial: imx: ensure UCR3 and UFCR are setup correctly
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+
+commit 6df765dca378bddf994cfd2044acafa501bd800f upstream.
+
+Commit e61c38d85b73 ("serial: imx: setup DCEDTE early and ensure DCD and
+RI irqs to be off") has a flaw: While UCR3 and UFCR were modified using
+read-modify-write before it switched to write register values
+independent of the previous state. That's a good idea in principle (and
+that's why I did it) but needs more care.
+
+This patch reinstates read-modify-write for UFCR and for UCR3 ensures
+that RXDMUXSEL and ADNIMP are set for post imx1.
+
+Fixes: e61c38d85b73 ("serial: imx: setup DCEDTE early and ensure DCD and RI irqs to be off")
+Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+Acked-by: Mika Penttilä <mika.penttila@nextfour.com>
+Tested-by: Mika Penttilä <mika.penttila@nextfour.com>
+Acked-by: Steve Twiss <stwiss.opensource@diasemi.com>
+Tested-by: Steve Twiss <stwiss.opensource@diasemi.com>
+Cc: Chris Ruehl <chris.ruehl@gtsys.com.hk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/tty/serial/imx.c | 14 ++++++++++++--
+ 1 file changed, 12 insertions(+), 2 deletions(-)
+
+--- a/drivers/tty/serial/imx.c
++++ b/drivers/tty/serial/imx.c
+@@ -2151,7 +2151,9 @@ static int serial_imx_probe(struct platf
+ * and DCD (when they are outputs) or enables the respective
+ * irqs. So set this bit early, i.e. before requesting irqs.
+ */
+- writel(UFCR_DCEDTE, sport->port.membase + UFCR);
++ reg = readl(sport->port.membase + UFCR);
++ if (!(reg & UFCR_DCEDTE))
++ writel(reg | UFCR_DCEDTE, sport->port.membase + UFCR);
+
+ /*
+ * Disable UCR3_RI and UCR3_DCD irqs. They are also not
+@@ -2162,7 +2164,15 @@ static int serial_imx_probe(struct platf
+ sport->port.membase + UCR3);
+
+ } else {
+- writel(0, sport->port.membase + UFCR);
++ unsigned long ucr3 = UCR3_DSR;
++
++ reg = readl(sport->port.membase + UFCR);
++ if (reg & UFCR_DCEDTE)
++ writel(reg & ~UFCR_DCEDTE, sport->port.membase + UFCR);
++
++ if (!is_imx1_uart(sport))
++ ucr3 |= IMX21_UCR3_RXDMUXSEL | UCR3_ADNIMP;
++ writel(ucr3, sport->port.membase + UCR3);
+ }
+
+ clk_disable_unprepare(sport->clk_ipg);