patch "Revert "serial: imx: initialized DMA w/o HW flow enabled"" added to tty-linus

patch "Revert "serial: imx: initialized DMA w/o HW flow enabled"" added to tty-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    Revert "serial: imx: initialized DMA w/o HW flow enabled"

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 907eda32a36fcdb979bdb91ea097abb3dd2c23c9 Mon Sep 17 00:00:00 2001
From: David Jander <david@protonic.nl>
Date: Fri, 26 Jun 2015 08:11:30 +0200
Subject: Revert "serial: imx: initialized DMA w/o HW flow enabled"

This reverts commit 068500e08dc87ea9a453cc4a500cf3ab28d0f936.

According to some tests, SDMA support is broken at least for i.MX6 without
HW flow control. Different forms of data-corruption appear either with
the ROM firmware for the SDMA controller as well as when loading Freescale
provided SDMA firmware versions 1.1 or 3.1.

Signed-off-by: David Jander <david@protonic.nl>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/imx.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 2c90dc31bfaa..54fdc7866ea1 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1121,11 +1121,6 @@ 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;
@@ -1143,9 +1138,6 @@ static int imx_startup(struct uart_port *port)
 	writel(USR1_RTSD, sport->port.membase + USR1);
 	writel(USR2_ORE, sport->port.membase + USR2);
 
-	if (sport->dma_is_inited && !sport->dma_is_enabled)
-		imx_enable_dma(sport);
-
 	temp = readl(sport->port.membase + UCR1);
 	temp |= UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN;
 
@@ -1316,6 +1308,11 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 			} else {
 				ucr2 |= UCR2_CTSC;
 			}
+
+			/* Can we enable the DMA support? */
+			if (is_imx6q_uart(sport) && !uart_console(port)
+				&& !sport->dma_is_inited)
+				imx_uart_dma_init(sport);
 		} else {
 			termios->c_cflag &= ~CRTSCTS;
 		}
@@ -1432,6 +1429,8 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (UART_ENABLE_MS(&sport->port, termios->c_cflag))
 		imx_enable_ms(&sport->port);
 
+	if (sport->dma_is_inited && !sport->dma_is_enabled)
+		imx_enable_dma(sport);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
-- 
2.4.6