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serial: mvebu-uart: clear state register before IRQ request 

When receiving data on RX pin before ->uart_startup() is called, some
error bits in the state register could be set up (like BRK_DET).

This is harmless when using only the standard UART (error bits are
read-only), but may procude an endless loop once in the extended UART
RX interrupt handler (error bits must be cleared).

Clear the status register in ->uart_startup() to avoid this situation.

Signed-off-by: Allen Yan <yanwei@marvell.com>
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Allen Yan 2017-10-13 11:01:52 +02:00 committed by Greg Kroah-Hartman
parent 68a0db1d7d
commit 2ff23c4802
1 changed files with 6 additions and 0 deletions
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6
drivers/tty/serial/mvebu-uart.c
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@ -322,6 +322,12 @@ static int mvebu_uart_startup(struct uart_port *port)
writel(CTRL_TXFIFO_RST | CTRL_RXFIFO_RST,
port->membase + UART_CTRL(port));
udelay(1);
/* Clear the error bits of state register before IRQ request */
ret = readl(port->membase + UART_STAT);
ret |= STAT_BRK_ERR;
writel(ret, port->membase + UART_STAT);
writel(CTRL_BRK_INT, port->membase + UART_CTRL(port));
ctl = readl(port->membase + UART_INTR(port));