On Tue, Jul 23, 2019 at 10:36:32AM -0400, Robert Middleton wrote:
> When closing and shutting down the exar serial port, if the chip
> has not finished sending all of the data in its buffer, the
> remaining bytes will be lost. Hold off on the shutdown until the
> bytes have all been sent.
>
> Signed-off-by: Robert Middleton <robert.middleton@xxxxxxxxxx>
> ---
> drivers/tty/serial/8250/8250_exar.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
> index edd6dfe055bf..f58eeb670b15 100644
> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -19,6 +19,7 @@
> #include <linux/string.h>
> #include <linux/tty.h>
> #include <linux/8250_pci.h>
> +#include <linux/delay.h>
>
> #include <asm/byteorder.h>
>
> @@ -457,6 +458,26 @@ static irqreturn_t exar_misc_handler(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> +static void
> +exar_shutdown(struct uart_port *port)
> +{
> + unsigned char lsr;
> + bool tx_complete = 0;
> + struct uart_8250_port *up = up_to_u8250p(port);
> + struct circ_buf *xmit = &port->state->xmit;
> +
> + do {
> + lsr = serial_in(up, UART_LSR);
> + if (lsr & (UART_LSR_TEMT | UART_LSR_THRE))
> + tx_complete = 1;
> + else
> + tx_complete = 0;
> + msleep(1);
> + } while (!uart_circ_empty(xmit) && !tx_complete);
What if the hardware is locked up? Will this sit and spin forever?
Shouldn't you also have a timeout for the flush?
thanks,
greg k-h
