From 7e11577ef6f31faf4a505e7823bf78b679906aca Mon Sep 17 00:00:00 2001 From: Lucas Stach Date: Fri, 4 Sep 2015 17:52:42 +0200 Subject: [PATCH] serial: imx: re-enable DMA support without hardware flow control 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 Acked-by: Jiada Wang Signed-off-by: Greg Kroah-Hartman --- 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 f1366cf4e6a9..dcbfa5e1fb34 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1125,6 +1125,11 @@ 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; @@ -1142,6 +1147,9 @@ 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; @@ -1312,11 +1320,6 @@ 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; } @@ -1433,8 +1436,6 @@ 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); } -- 2.39.2