Hi Miquel,
On ven., oct. 06 2017, Miquel Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx> wrote:
> From: Allen Yan <yanwei@xxxxxxxxxxx>
>
> 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
produce
> 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@xxxxxxxxxxx>
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
Thanks,
Gregory
> ---
> drivers/tty/serial/mvebu-uart.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c
> index 81a3d2714fd3..67f302748b78 100644
> --- a/drivers/tty/serial/mvebu-uart.c
> +++ b/drivers/tty/serial/mvebu-uart.c
> @@ -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));
> --
> 2.11.0
>
>
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--
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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