From bc764b8fdb4346cb21f624e08231267d0ea9578b Mon Sep 17 00:00:00 2001 From: Shawn Guo Date: Mon, 8 Jul 2013 15:53:38 +0800 Subject: [PATCH] serial: fsl_lpuart: restore UARTCR2 after watermark setup is done Function lpuart_setup_watermark() clears some bits in register UARTCR2 before writing FIFO configuration registers as required by hardware. But it should restore UARTCR2 after that. Otherwise, we end up changing UARTCR2 register when setting up watermark, and that is not really desirable. At least, when low-level debug and earlyprint is enabled, serial console is broken due to it. Fix the problem by restoring UARTCR2 register at the end of function lpuart_setup_watermark(). Signed-off-by: Shawn Guo Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/fsl_lpuart.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 263cfaabe9e2..7bc17f21062a 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -342,8 +342,10 @@ static void lpuart_break_ctl(struct uart_port *port, int break_state) static void lpuart_setup_watermark(struct lpuart_port *sport) { unsigned char val, cr2; + unsigned char cr2_saved; cr2 = readb(sport->port.membase + UARTCR2); + cr2_saved = cr2; cr2 &= ~(UARTCR2_TIE | UARTCR2_TCIE | UARTCR2_TE | UARTCR2_RIE | UARTCR2_RE); writeb(cr2, sport->port.membase + UARTCR2); @@ -366,6 +368,9 @@ static void lpuart_setup_watermark(struct lpuart_port *sport) writeb(2, sport->port.membase + UARTTWFIFO); writeb(1, sport->port.membase + UARTRWFIFO); + + /* Restore cr2 */ + writeb(cr2_saved, sport->port.membase + UARTCR2); } static int lpuart_startup(struct uart_port *port) -- 2.20.1