The commit enabling DMA support even if no flow control is present
was reverted on the grounds that it uncovered a number of bugs in
the code that lead to hanging tty devices and/or missing characters.
After tracking down the issues it is clear that those were generic
bugs and had nothing to do with flow control being present or not,
only that allowing DMA without hardware flow control increased
the exposure of that code a lot.
Now that those bugs are fixed, it should be safe to re-enable DMA
support.
Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
---
drivers/tty/serial/imx.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 792a1e1adc01..ac19fff5175c 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1121,6 +1121,11 @@ 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;
@@ -1138,6 +1143,9 @@ 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;
@@ -1308,11 +1316,6 @@ 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;
}
@@ -1429,8 +1432,6 @@ 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
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