Commit 2ff23c48 authored Oct 13, 2017 by Allen Yan Committed by Greg Kroah-Hartman Oct 20, 2017

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>

parent 68a0db1d

drivers/tty/serial/mvebu-uart.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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));